Wow, thanks for all of that! I'll try to give my thoughts and current but mouldable views on some of the points that you've all raised.
Air Conditioning
At the moment this is fairly low on our list of priorities. Our plans will be to travel in the Americas in the more comfortable seasons for each region - ie. Canada in the summer, Death Valley in the winter etc. so with the pop top being able to be fully open and a tropical roof of solar panels on top I feel we will remain comfortable. We've survived Greece in the summer in our current motorhome which has massive untinted roof vents all along it with no air con and mine will be much better insulated than that. It is however something I think that we might add in the future for long term travel in Australia when keeping below the magic 4500kg isn't as much of an issue. I must admit I wouldn't have thought the 240V AC would be so much more efficient than those Earthcruiser style Arctic Breeze units! But alas, you are correct
Suspension and wheels
This will be the first addition to the build to make sure clearances are correct for the tanks, subframe etc. At the moment I like the look of Kym's 17" rims and the kinds of standard tyres that go with them as I hope that my camper will be on the light side and suitable for said tyres. The 19.5" seem like they might be overkill for the weights I'll be carrying and perhaps limit my tyre choice around the world. (Please correct me if I'm wrong or if you have another suggestion!). I understand that they are steel and heavier than the alloys but perhaps that's just something I'll have to factor in. Still need to continue my research on suspension. Sounds like parabolics are the bees knees but don't offer a massive gain in performance over tuning a spring pack either myself or professionally using leaves from other models. If a spring breaks in Bolivia, is it going to be easier to replace or at least get going again having an intimate knowledge of how my springs are put together and what's required to fix it? I assume any replacement for the parabolics will have to come from ATW? Still lost on shocks. Seems to be a lot of options out there! Adjustable sounds good to me. Apart from that, need more reading...
Engines
Call me a fuddy duddy but I prefer the idea of not messing about with the engine too much and performing such a change as adding a turbo to the 4.2L. I've seen that plenty of people on just this forum alone have done exactly that with great success but if I can manage to find a 3.9L in good condition (not to mention with it's more standard 12V) I think I'll go for that. A tidy and well priced FG84 would tempt me as well.
Charging capacity
As much as possible... I'll be covering the roof with solar and adding the largest MPPT that I can afford to handle it. But this will actually be secondary to making sure the alternator is up to the task of thumping in as much as possible. Our travel style usually means that we don't stay in one place for more than one night. We drive a lot! I would like as much as is reasonable to run off the batteries that I will have spent considerable time and finances beefing up. I know 800Ah of LiFePo4 seems a little excessive but with that capacity they should have a fairly easy life even when running a few thousand watts of induction. The stated life of 2000 cycles should be achievable this way.
Cooking
This brings me to cooking. WhereisFranklin hit the nail on the head as I was thinking to do exactly the same thing. Two portable induction cookers (probably still set into the kitchen bench) and a third for a spare/cooking outside. Lunchbox butane cooker as backup. Charcoal BBQ. Despite hopefully having a thermally efficient roof, I will likely add some sort of extractor fan in the roof over said cooktops.
Heating
This isn't an option and will be going into the build from the beginning. Many decisions still to make here. Again, I never would have even looked at using 240V AC to do this but you've pointed me in the direction of a few threads that I've now seen that describe this in detail. Love a bit more research... The electric heated towel rail sounds like an extremely logical solution if I don't go down the hydronic route too.
Travel Style
I 100% understand those that say they spend most of their time outside, but we are looking to eventually be travelling full time in this rig so I will be unashamedly building in the creature comforts! We enjoy the feeling of being cosy and comfortable inside our vans in the inclimate weather and don't find much joy in the feeling of constantly 'rouging' it. Hence the want for a 4.5T Canter and not a readybuilt troopy. Very soft, I know... Having said that, everything is a compromise and things like air-con will happily be left at the wayside for the sake of things like not having to have an inspection every year.
Sub frame
I'd say I'll be going the spring mounted route as there is more than enough information out there to make informed decisions about its design and to me it just makes sense.
Toilet
The composting toilet is a new concept to me and will require a bit more investigation. Your positive comments are the sort that will make me tempted to go that route. We currently use a chemical toilet which is by far the most practical for European travel and I just assumed I'd do something similar in the Canter but perhaps with the SOG system to cut out our need for chemicals. I won't ask for any more info on the composting toilet here until I've read what you've all already written! As you said steve66, mounting it on slides in the shower is the way to go. My shower/toilet will be the entranceway to the camper.
Has someone on here done a nice hard walled shower in a soft walled pop top camper?
Panels and thermal efficiency
I feel as though I'd bear the cost of some slightly thicker wall panels as I will feel better about the finished build, knowing that it is wonderfully efficient. I think I will be in the same boat LeishaShannon, without LPG and all systems (that I can fit) all mounted inside the box for protection against freezing, the waste heat of these appliances may be quite high. This is one of the reasons I'd like to go down the canvas pop top route. Not only because I need to for containerisation, but so in the warmer months it can all be completely opened up to let as much of this heat out quickly and efficiently. I'll be aiming to do the EC style multi layered canvas to try and keep in as much of that heat in the winter. We will be able to sleep with the top down too. I haven't even made contact with any of the companies at this extremely early stage of planning and I will likely take a tour around their facilities/pay a general visit to see what each has to say. I'm just happy with the fact that I've found 3 companies so far in SE QLD! Spoilt for choice! Really looking forward to getting into the proper research on that part of it and seeing what I can find that will optimise my build.
Design
Everything will be fully 3D modelled with CAD/CAM software so that not only can I see if everything is going to fit and have plans ready to send out to suppliers, but I'll also be able to program the machining of any custom components right from the same software. I also plan to build something similar to this CNC router for accurately cutting out my interior panels -
https://www.maslowcnc.com/ - a nice little side project...
Fridge
Once again I didn't think I'd be looking down the route of 240V and with a very low profile pop-top I may still not be able to. As far as I'm aware, bar fridges are famously inefficient and surely an upright 90L Engel (which would be more than enough for our initial needs as a couple) would consume less power than that. If you have a small fridge in mind that will outperform it please let me know! Obviously with the lack of gas I won't be going for a 3 way fridge. The 90L 3 way Dometic in our current motorhome really struggles in the high temperatures.
Insurance
Thanks for the tip WhereisFranklin, that seems pretty reasonable. Traveling through the Americas is going to be a different ballgame though. Yet more research! Just glad its not a several 100k dollar build that I'll be trying to insure...
I've given myself a time limit of 12 months full time to finish the build - otherwise, knowing myself, I will drag it out for years. Also, does anyone have a pdf of the
body builder manual for the FG649? Most of the links I've found seem to be dead and from what I can see it's dropped off the official website.
Quite a long post I know, about ideas that are in their infancy. My main goal over the next 12 months before we return to Australia is to have some of these concepts nailed down and hopefully have a truck on the driveway or at least one ready to view. I won't be doing much detailed and dimensioned design work until I have the actual base vehicle as this could vary up until the end. But to keep to the year I've given myself to build it, all this thinking needs to happen now I think.
Hopefully I've replied to what most of you have taken the time and care to write out for me. Nothing is set in stone and I enjoy my views being challenged. It's much appreciated
