Aluminum Flat-bed-canopy Colorado Diesel Build

[R_Lefebvre]

Sooo... I started this build in March 2021. I blame it mostly on the pandemic lockdown. After too much YouTube surfing of overland stuff, I got inspired my Australian flatbed/canopy setups, and with nothing else better to do since everything is shut down, I just kinda jumped in with both feet. I didn't think I wanted to do a build thread here, but lots of people like what I'm doing elsewhere, so might as well share.

I thought it would be a 2-3 month project, but as usual, I was wrong. Here it is January 2022 and I'm still at it. And that's OK. Still locked down here in Ontario, Canada...

This build is sort of the culmination of my experiences with overland trucks. My first, which I still have, was a Disco 2 I built out pretty nicely. But very quickly found that it was simply not big enough for a family, can't tow much, etc. After that I bought a Nissan Frontier but didn't do too much with it other than a camper shell. It gave me way more space than I had in the Rover, but it was a royal PITA getting stuff in and out of the back of that camper shell bed. Especially if I was towing. I wasn't interested in the Decked system or anything like that, because I find they are very space inefficient and weigh too much. It was nice to have the covered storage of the camper shell, but it just didn't work well IMO. Then, I started seeing what the Australians do, and it just makes so much sense. No more crawling around in the bed of the truck, easy access, especially when towing something. But the prices for these things are eye-watering, and not really available in North America anyway. So I set to work!

One of the key design aspects, and how I differed from the 'Straylians, was that I would never have need of a naked flatbed. I have trailers for that. And so to save weight on structure (double floors, etc.) I just built the thing as one piece, rather than having a separate lift-off canopy. Another aspect of the design, is that I have a pretty well outfitted shop, but I don't have access to a sheet metal brake. So it's all designed to use 6061 structural tubing, and flat plate. This means a lot of welding, but should be much stronger, both because of the alloy, and because the box sections.

I designed the whole thing in Fusion 360 which I'm pretty familiar with. The design kinda progressed along with the build, I didn't do all the design and then start building. No no, my ADHD wouldn't allow for that. But I don't see the point showing the progression of the design, so I'll just go ahead and start with the latest design:

 

[R_Lefebvre]

And here's where it all got started last March. My family helped me lift the back off. I estimate the weight of the bed to be about 150lbs, just based on the fact that my family was able to lift it without anybody getting hurt. The tailgate was another 40 lbs roughly. So, call it 200lbs even, and figure that a fiberglass cap is about 200lbs, and if this thing works out to be 400lbs. CAD is saying 429lbs including the roof rack over the box, but not including the spare tire carrier, ladder, jerry can box, etc. Also not including the rear winch mount/towbar. But I've also removed/replaced the rear towbar and bumper, so these are about a wash. So I'm not doing too badly I think.

It was about this point that my parents and in-laws started thinking I'd lost my mind "doing that to a perfectly good truck."

 

[R_Lefebvre]

I spent a few hours under the truck with a plumb-bob, trying to reverse-engineer the chassis mount points.

Pro-tip: A week or so later, I found that GM makes chassis-cab drawings freely available on the internet:

 

[R_Lefebvre]

The frame came together in about a weekend. Which gave me a false sense of confidence this would be done by summer.




Added the lights. These are Chinese things from Amazon, and I'm not sure they'll last, so I mounted them via intermediary plates that will be easy to change. If anybody has a lead on good quality tail lights that don't look like basic trailer lights, please let me know. Wiring these up became a massive headache because of the separated turn signs. I wanted turn signals, because they're just so much better than American style lights. But I didn't realize what I was getting myself in for. I tried a trailer wiring splitter, but I was not at all happy with the performance. The hazard flashers didn't work properly, and IIRC, the brake lights flashed every time you turned on the turn signals. Or vice versa. It was a mess and just not acceptable to me. Turns out the only way to get a good clean turn signal, was to tap into the turn signals up front and pull wires to the back. Similarly, the only way to get good clean brake lights, was to pull a wire from the fuse box for the CHMSL.

Also, you can just see I frenched in the factory rear view camera.




So uh, this is why you don't drive trucks off road with no fenders.



Then I added the decking, and I was pretty happy with how this came out. I think you could play pool on it. The decking is 1/8" 6061 plate.

 

[R_Lefebvre]

Next, I had to work on the new trailer hitch, which eventually morphed into a rear winch mount. In my experience, I've needed to winch backwards more than forwards anyway. Which I could never do of course. I do plan to probably add a winch up front too. The tow bar is made from 3/16" 2x6 steel tube with the support rails made from 1/4" angle and plate. You can see the I frenched in a 7-pin trailer connector. In hindsight, it's a bit close to the safety chain loops. It works, it's just a little more fiddly to hook up than I'd like. That being said, there wasn't a lot of room to put it without compromising something else, most notably ground clearance. The square hole on the other side is for a 50A Anderson plug for the camper umbilical.

For the design of the trailer hitch, I wanted to try to gain ground clearance. But I tow a LOT, and I didn't want to compromise that too much. One of my good buddies is a truck engineer at an American OEM, and he informed me that relying on too long of a drop hitch is bad for a lot of reasons, and I wanted to avoid that. So I ended up with the hitch tube only about 2" higher than the factory one. However, I still gained a lot of ground clearance on the sides where it really matters.



Painted and covered in bed liner. Winch installed. There is still enough room above to fit a trundle drawer.



Next, I started on the uprights for the box. These are 2.5" 1/8" 6061. I don't have a lot of other good photos of the box construction. It had been almost a decade since I welded, but I was starting to get pretty decent at it by this point.




One of the key design features of this thing, was the ability to fit 4 mountain bikes in back. I want to be able to carry the family bikes nice and dry and secure during camping trips.

 

[R_Lefebvre]

Somewhere around early June, work on the truck stopped, as we had made the decision to downsize our camper. We had a 2014 Coachmen Apex 23' footer, at the time it was the smallest I could get with bunk beds which were important for us. I towed it with the Nissan, and it did it, but it wasn't fun. I was also inspired by the Australian off-road campers, but they are extremely expensive, not available here, and they're also very heavy which is something nobody talks about. I've got experience towing a 2000 lb overland trailer, and I know that you're not pulling these big campers very far off road, no matter how tough they're built. It's just a matter of physics. But, I still wanted something easier to tow, more manoeverable, and lighter, just to make getting into some more rugged camping spots easier. I also knew I wanted a full off-grid power system, and I didn't want to put that money into a 7 year old trailer. Then I found these Winnebago Micro Minnies. It ticked all the boxes. Only 7' wide, and they have an 18 footer with bunk beds! And no slide! Better insulation. Rubber torsion axles. Off-roady tires. Stonger frame. A brighter, more modern interior. So we made the deal, and I got to work with the power system, which took about a month. 510 Ah of lithium, 400W solar, 3000W inverter. But I'll save that for another thread, though I'm not sure it belongs on ExPo. I call this my Fauxverland Trailer. This was taken on our shakedown weekend before I started all the work on it.



That work took until the end of July, with a few weekends off for camping, etc We were planning on taking our first big trip, driving from Ontario to British Columbia, in August. This is the first job I'd ever had where I could take that much time off. But, the fires out west made us think twice, and we ended up going out east to the Maritimes instead. The first week of my 4 week vacation was spend tidying up lose ends. I wanted to have something like fenders and mudflaps on it so as not to tear up our new trailer. I don't have pictures of that process, but I just have some from the trip. The rear mudflaps are intended to be mounted on quick release pins. Something I pioneered on my Land Rover and works really well so they don't get ripped off off-road. And I decided not to do under-bed cargo boxes behind the rear wheels like the Australians do, because I find that the volume-to-weight ratio just isn't worth it. And I can use that space for other things like a 4 gallon air tank, and I'm not sure what yet on the other side. I was going to put a battery there, but it just won't fit well, and is too far back anyway. Also, I worked in some utility steps into the side panels in front of the wheels.

Here we are camping somewhere at a little municipal roadside stop near Gaspe. This was our first experience using iOverlander, and for the most part we really liked it. Being able to camp anywhere, with no hookups but full service, is really liberating. We were out for about 3 weeks, camped about half the time at provincial parts, and half at iOverlander stops. I didn't take a lot of pictures of the camp setups, that's not really what I'm doing it for.



Overall the truck did amazing on this trip. Especially because of the diesel. I LOVE it. I think we averaged about 15 MPG over the trip pulling this trailer. And I saw some ridiculous numbers like 18 MPG at 50 mph on flat land. But the real benefit (there really is no economic justification for the diesel) is just how stress-free it was. The Nissan had way more power. But you always KNEW that you were caning a car engine. This thing pulls like a freight train. It's slow, but feels like it will do it all day. Pulling up hills, it's quiet, not revving it's brains out. Going down grades, the exhaust brake makes it trivial. I mean seriously. I went down 18% grades without really having to use the brakes at all.

That being said, the trailer is a bit disappointing. Not terrible, but not the build quality I expect from Winnebago. Nothing structural, but basically all the plumbing leaked. Every single joint. I spent many hours on the trip being Mr. Plumber fixing leaks, also because Winnebago was completely unhelpful on warranty. I tried to get help on one, and they suggested I drop it off at a dealer in Halifax. End my trip and go home, and they dealer would look at it in 3 weeks. Give me a break. It's like they don't even understand the product they're selling.

 

[R_Lefebvre]

Oh, I almost forgot to mention. You might have noticed I added low-profile strut channel as rails inside the box. Both as stiffeners for the front/rear/roof panels, but also as tie-down points, and for bolting in furniture in the future.

And I also forgot to mention, it was a few days into that trip before the fear of hearing a BANG and seeing my trailer leaving the roadway, connected to a sheared off trailer hitch, finally left me.

After we got back from the trip, I had determined I needed new rear springs. It wasn't the weight of the box, it only weighed about 200lbs at this point. Just that trailer had about 700lbs tongue weight the way it's set up, and I could not crank enough on the weight distribution bars to level it out. I found the Nissan was the same way (only worse, even). Plus, I need to be able to tow without the WD hitch, because you don't want to attempt anything off-road, even including simple articulation, with the bars on. I actually bent a set already on my motorcycle trailer. I thought about the Add-A-Leaf, but I ended up doing the "buy the best once, cry once" thing and ordered Old Man Emu HD spring packs. However, this presented a bit of an issue. I do NOT want to lift the truck much at all. The ZR2 is already lifted 2" anyway. And being buddies with somebody who does truck engineering professionally, I'm just not interested. And the OME HD's were going to lift it about another 2". Luckily, a little engineer finagling and I realized that I could take the factory OEM lift blocks from under the spring pack, install them on top of the springs but under the bumpstops to retain my bumpstop travel and not destroy my shocks. Voila! I now had about an inch more pre-load, my more rate, and everything is much better, especially with a trailer hooked up. It's stupid, but it works. You can also see where I cut off the factory exhaust.




Also, at some point, I chose new wheels. I went with 16x8 Black Rhino Chambers. I wanted to go down an inch in size, so I could get more sidewall without going to super huge tires. I had decided to stay about 33", again, in consultation with my buddy. With the way I use the truck, I didn't want the compromises that come with a 35" tire, even though they can be made to fit on this truck. Unfortunately, I couldn't find wheels that I liked, and that met other desired characteristics (load rating, price, etc.) that had the offset I wanted (about 15-20mm vs. 33mm stock). These are 0mm, and so are pushing out more than I'd like. But it was the compromise I had to accept. On road it steers fine, but you can really feel the Weight Jacking in some off-road situations. Here I am test fitting the wheels for brake clearance. No problem, lots of clearance. (OEM wants to see about 5mm)



For tires, I ended up choosing Cooper Evolution M/T's. It's my first time going to full M/T's, but I figured what the heck. I had another set of 32" Yokohama G015's on the stock wheels that I will use for winter, and towing the big trailer on long trips. So I can have a bit of fun with these, and the Evolutions are a bit more on the tamer side. But they have a pretty serious military look to them that I love and really fit with the wheels too. And I've had great luck with many sets of Coopers in the past so the choice was pretty easy.

However, once I got them on, I realized there was no way they'll fit without some major trimming. I couldn't even get out of my driveway like that. The situation was made much worse by the 0mm offset. I didn't tell my wife I had kinda been planning on doing AEV Highmarks anyway, but not my hand was force. And while I'm at it, let's just do that snorkel too. The snorkel, if I'm honest, mostly because it looks cool. IMO, anybody who says they really are functional, is either lying to you or themselves. I probably could have gotten away with the AEV 33" trim kit, but I'm not sure with this offset. It might have cleared, at the mall, but when things start moving around in the real world (control arm bushings are a thing) I didn't trust there was enough clearance. And even AEV suggests you should lift the front a bit, but again: no lift for me. Plus, I find the filler panels looks a little janky. In the end, I love the look of the Highmarks, I have tons of clearance to the 33's and never have to worry (even with 35's you do), and I really like the way AEV did the filler plates. It was a hell of a lot of work though!




I did all the work myself. But I generally don't trust mechanics, certainly don't know any that I would anyway. The filler plate was kinda scary with how much you have to cut off. In the end, I'm happy with the job I did.

 

[R_Lefebvre]

Here is the setup all installed. Despite the engineering compromise for the 0mm offset, I do like the stance quite a bit.



Somewhere along the way, I had built a rear tire carrier. This will also be the base for the rear ladder system.




Here is a better view of the tire rack. Also, the wing things, are flying buttress supports for the roof rack that will be extended out over the rear tire carrier. More inspiration from the Aussies. Might as well make sure of as much of the OAL as I have anyway.




Here I am checking the tire clearance with my redneck RTI ramp. More clearance than some 35" tire trucks from OEM, I'm told. So I'm happy with that. This may not quite be full flex, but it's a pretty friendly surface to rub on in any case.

 

[R_Lefebvre]

Here is where I'm adding a J-trim to hold the door bulb seal. I was afraid of how this would go, but it actually went quite well.




At least it was, until this happened. So... funny thing... 304 stainless filler rod looks an awful lot like 4043 when you're not paying attention... And amazingly, it kinda sort even welds in. So, I had to grind this cancer out, which sucked. But actually not too bad and I was able to close the hole. I love TIG.



But, somewhere along the way, apparently I got pretty OK at this welding thing?

 

[R_Lefebvre]

Oh, also I spent much of November reorganizing the garage so the truck can fit in with the door closed, insulating the garage and adding a heater so I can keep working in the winter. We're still locked down here in Ontario. So, ******, might as well make the best of the opportunity.

So here's about where I'm at right now. I've got the roof rack over the back done, one door, and one fender flare. I thought about using light-gauge trailer fenders, but I couldn't find any that fit, and you just know those things bend if you look at them the wrong way. So, I crafted one out of aluminum plate again. Similarly with the doors. I almost had some bent up for me, but I wasn't happy with the price, timing and service on quotes I was getting from local shops, and with nothing else to do during the Christmas break... might as well weld. This design I think actually came out a little better than they would have been from bent sheet anyway. Much stronger, you can stand on them. And they can function a bit like a bed rack, I plan to hang traction boards in the recess, maybe a shovel... will see what fits. I have a little grinding to do to clean up some of the puckers, but I think it'll look quite fine when covered in black bedliner.

You can also see the rear flood lights on the back of the rack, and some 5000lb swivel E-track tie-downs in the corners of the bed I added at some point.

 

[Utah Mountains]

I freakin' love this build. Nice work! It's good to see you using it as you're building it and responding to stuff you learn along the way.

 

[ITTOG]

Oh, also I spent much of November reorganizing the garage so the truck can fit in with the door closed, insulating the garage and adding a heater so I can keep working in the winter. We're still locked down here in Ontario. So, ******, might as well make the best of the opportunity.

So here's about where I'm at right now. I've got the roof rack over the back done, one door, and one fender flare. I thought about using light-gauge trailer fenders, but I couldn't find any that fit, and you just know those things bend if you look at them the wrong way. So, I crafted one out of aluminum plate again. Similarly with the doors. I almost had some bent up for me, but I wasn't happy with the price, timing and service on quotes I was getting from local shops, and with nothing else to do during the Christmas break... might as well weld. This design I think actually came out a little better than they would have been from bent sheet anyway. Much stronger, you can stand on them. And they can function a bit like a bed rack, I plan to hang traction boards in the recess, maybe a shovel... will see what fits. I have a little grinding to do to clean up some of the puckers, but I think it'll look quite fine when covered in black bedliner.

You can also see the rear flood lights on the back of the rack, and some 5000lb swivel E-track tie-downs in the corners of the bed I added at some point.

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Nice build but even better sign above the truck.

 

[2025 deleted member]

Amazing craftsmanship!

 

[Thinkofsomethingkwik]

How does insurance work on this rig? I was under the impression that any flatbed truck had to be registered commercially?

 

[2025 deleted member]

How does insurance work on this rig? I was under the impression that any flatbed truck had to be registered commercially?

Not in the USA, maybe with a certain carrier but not as a general rule
Edit- if this is Canada I have no idea…lol