Balancing bed length, truck length, and camper overhang

[ReluctantTraveler]

Hey y'all, been a while! Those of you who know me already know I'm planning out a DIY hard-side camper build for my family of four (plus dog).

I'll be building on an F-550/5500 platform with a 12' flatbed, and I'm currently trying to weight the tradeoffs of overall rig length vs. interior living space. For simplicity and ease-of-build, the right will NOT have any slides.

According to Ford, the truck I'm leaning towards is 24' long. I don't have enough experience with flatbeds to know if they add any length beyond the end of the frame or not.

I'm considering extending the box 2' beyond the end of the flatbed, which would add a considerable amount of interior space and storage (I'd still keep the heavy stuff between the axles), but obviously also push the length of the entire right out another 2' as well.

While I do plan on boondocking a fair bit more in this rig, I'm NOT planning to do any serious offroading. Mostly service roads, highway miles, national parks, and campgrounds. We DO take lots of extended trips (6 weeks+).

In your opinion, is it worth adding two feet to the rig for the added space, or would it be several limiting to my camping experience?

 

[IdaSHO]

In short, YES, adding livable space to the rear is beneficial, provided you actually need the space

Although I strongely suggest you hash out design of your camper first, being mindful of weights forward/back/left/right then work out what it needs to haul it effectively.

In our case, our design allowed us to stick with a standard 8' bed, with 24" added to the rear of the camper, but also added 24" to the end of the chassis to allow for the large cross-body box.
Our camper is built with a significant weight forward bias so it works great as designed. And adding 24" to the rear of the chassis avoided any significant alterations to the frame and running gear.
This also allowed us to maintain the short wheelbase. We are longer than a crew cab with a 10'camper, and our turning radius is MUCH tighter.

 

[Peter_n_Margaret]

In Oz the maximum legal rear axle overhang is 60% of the wheel base.


Cheers,
Peter
OKA196 motorhome

 

[DzlToy]

Depending on the type of trail riding or travelling you are going to be doing, 30% - 40% may be a better plan.

Sample Truck: CC SB USDM pickup with a 150" wheelbase and a 36" tire

At 60% rear overhang, you could have 6 Feet of body behind the rear tire. This is going to cause lots of problems unless your body is quite high, you have huge tires, you chamfer the body or you stay on paved or graded dirt roads. Imagine the bed of that same truck completely behind your rear tires. Mock this up on your truck, measure departure angles and tail swing, etc.

At 40% rear overhang, you still have 42" of body behind the rear tire. While this isn't Jeep or Gelandewagen territory, it is much more manageable.

Add lightness, simplicity and serviceability. Don't add spaces, bins or boxes that aren't absolutely necessary. You WILL fill them up, adding weight and changing the balance and handling of your vehicle. Don't bring everything in your house/shop with you. People travel the world on foot, motorcycles and in comparatively small vehicles such as 40 and 70-Series Land Cruisers. More is rarely better; it's just more.

Edit: I often hear things like, "I am not rock crawling, so I don't need low gears." or "I will be staying in campgrounds, so I don't need a lot of clearance." Try turning a fat, long, heavy truck into a tight parking space, in city traffic or up a short, steep driveway and the design flaws become apparent. It's better to have it and not need it (low gears, short overhangs), than to need it and not have it. $0.02

 

[ReluctantTraveler]

In short, YES, adding livable space to the rear is beneficial, provided you actually need the space

Although I strongely suggest you hash out design of your camper first, being mindful of weights forward/back/left/right then work out what it needs to haul it effectively.

In our case, our design allowed us to stick with a standard 8' bed, with 24" added to the rear of the camper, but also added 24" to the end of the chassis to allow for the large cross-body box.
Our camper is built with a significant weight forward bias so it works great as designed. And adding 24" to the rear of the chassis avoided any significant alterations to the frame and running gear.
This also allowed us to maintain the short wheelbase. We are longer than a crew cab with a 10'camper, and our turning radius is MUCH tighter.

Thanks as always for the thoughtful reply, Kenny!

I had initially been considering the "dropped rear" design like you see on larger off-the-shelf truck campers, but I think the angled rear that you see in overland vehicles is a much better approach. The potential to bottom out up a steep driveway with the dropped rear just seems so high.

I've been trying to make my design work without the overhang for months, but with the size of our family and space needs, it's just not working the way I'd hoped for what we want to do.

My design has the heavy parts of the system (water, batteries) up near the front of the build, with the rear left mostly for storage. This should keep most of the weight between the two axles, I think.

 

[ReluctantTraveler]

In Oz the maximum legal rear axle overhang is 60% of the wheel base.

View attachment 799542
Cheers,
Peter
OKA196 motorhome

For the truck I want, that would be like 9', which is absolutely bonkers! We should be substantially shorter than that.

 

[ReluctantTraveler]

Depending on the type of trail riding or travelling you are going to be doing, 30% - 40% may be a better plan.

Sample Truck: CC SB USDM pickup with a 150" wheelbase and a 36" tire

At 60% rear overhang, you could have 6 Feet of body behind the rear tire. This is going to cause lots of problems unless your body is quite high, you have huge tires, you chamfer the body or you stay on paved or graded dirt roads. Imagine the bed of that same truck completely behind your rear tires. Mock this up on your truck, measure departure angles and tail swing, etc.

At 40% rear overhang, you still have 42" of body behind the rear tire. While this isn't Jeep or Gelandewagen territory, it is much more manageable.

Add lightness, simplicity and serviceability. Don't add spaces, bins or boxes that aren't absolutely necessary. You WILL fill them up, adding weight and changing the balance and handling of your vehicle. Don't bring everything in your house/shop with you. People travel the world on foot, motorcycles and in comparatively small vehicles such as 40 and 70-Series Land Cruisers. More is rarely better; it's just more.

Edit: I often hear things like, "I am not rock crawling, so I don't need low gears." or "I will be staying in campgrounds, so I don't need a lot of clearance." Try turning a fat, long, heavy truck into a tight parking space, in city traffic or up a short, steep driveway and the design flaws become apparent. It's better to have it and not need it (low gears, short overhangs), than to need it and not have it. $0.02

I appreciate the insights, but I would also like to note that I'd be cautious about giving "what works for me" advice as universal guidance.

We've done several long-distance road trips in a tiny as heck travel trailer, and had a good chance to evaluate what's worked for us, what hasn't, and what we do and don't need for the kind of travel we want to do.

Bare minimalism works great for some folks, but is not how I want to live if spending 6 weeks or more on the road. No judgement on folks who enjoy that. To each their own!

As noted above: everything is a trade off, and I'm trying to weigh which combination of concessions works best for our needs.

 

[DzlToy]

You asked for feedback on bed length, wheelbase and over hang ratios and several people have provided that. If you know what you need or want based on your experience or research, don't ask for opinions from other people.

Everything is a trade off, specifically large rigs with lots of room for people and gear, have longer overhangs, longer wheelbases and are generally quite heavy. If this is the kind of rig that you want so that you can travel for 6-8 weeks at a time, it sounds as if your mind has been made up. A crew-cab F-550 with a 12' flat bed on it, does not leave much room for flexibility. It kind of is what it is.

If you wish to consider shorter overhang or shorter wheelbase rigs to provide additional manoeuverability or have a lighter, more capable rig, then you cannot likely stay with the design above, which means you must consider other people's rigs, designs, opinions and down-sizing your gear and rig, to fit into a smaller space.

If you figure out how to build a Tardis, I will be your second customer.

 

[ReluctantTraveler]

Haha, well there it is !

And after all that asking.

That's one for the ExPo Classics.

If you don't understand the difference between things like "If you do X, Y will happen" or "if you care about X, you might consider Y" versus "don't do X, you don't need it," that says more about you than me.

 

[ReluctantTraveler]

Consider @IdaSHO's response, which provided details about his build and how he balanced his decisions, and @Peter_n_Margaret providing some "heads up don't go above this length" advice with the "you don't need space just be more nimble" response from @DzlToy.

I'm not trying to be a jerk. The folks on this forum have helped me tremendously.

There's just a tendency among some folks to get "overland purist" about things when not everyone is doing rock climbing in remote places.

 

[The Artisan]

Hey y'all, been a while! Those of you who know me already know I'm planning out a DIY hard-side camper build for my family of four (plus dog).

I'll be building on an F-550/5500 platform with a 12' flatbed, and I'm currently trying to weight the tradeoffs of overall rig length vs. interior living space. For simplicity and ease-of-build, the right will NOT have any slides.

According to Ford, the truck I'm leaning towards is 24' long. I don't have enough experience with flatbeds to know if they add any length beyond the end of the frame or not.

I'm considering extending the box 2' beyond the end of the flatbed, which would add a considerable amount of interior space and storage (I'd still keep the heavy stuff between the axles), but obviously also push the length of the entire right out another 2' as well.

While I do plan on boondocking a fair bit more in this rig, I'm NOT planning to do any serious offroading. Mostly service roads, highway miles, national parks, and campgrounds. We DO take lots of extended trips (6 weeks+).

In your opinion, is it worth adding two feet to the rig for the added space, or would it be several limiting to my camping experience?

You could always slant it to get the 2 feet. It could be seating or storage. I am building a hard sided poptopper pod for a client 14 on the floor slanted to 16 over all length. The slant lower will hold his fishing poles exterior and above a full wall of storage for the inside.
Kevin

 

[ReluctantTraveler]

You could always slant it to get the 2 feet. It could be seating or storage. I am building a hard sided poptopper pod for a client 14 on the floor slanted to 16 over all length. The slant lower will hold his fishing poles exterior and above a full wall of storage for the inside.
Kevin

Yea, I'm definitely leaning that direction! Originally was thinking have the rear dropdown like you see on some of those larger Lance/Arctic Fox models, but... it looks like it'd be hell to drive up steep driveways and the like. Angled for the win (apparently if you shorten this to the three letter acronym, Expedition Forum thinks its a swear?).

 

[ReluctantTraveler]

Perhaps. but then I'm not the one asking others the questions you are.


Indeed. From what I recall, very helpful.

Which is why I think your specific comment I quoted earlier was in bad form.

I read from the poster an opinion given, in response to a request in the OP for same.


What might be at issue here is you and I having difference understandings in the meaning, usage and expectations surrounding that word, opinion.

Which is fine by me.

But I' have spent enough time on here and "care" enough about the forum (sometimes) that when I read something I take issue with, I may call it out.

You are welcome to your own opinion on what that also says about me.

"Don't give absolutist advice" isn't in bad form