I for one am puzzled by the logic you have used to write off the aluminium and steel as a dumb idea. I'll note my experience for what it is worth. I lived (vs camping temporarily) in aluminium clad, steel or aluminium framed campers for many years (quite a few years ago now) and don't see the logic of your discussion playing out in reality.
Originally Posted by Ndmker
All other materials you have discussed could theoretically be damaged to some degree by the same sort of impact you mention that could damage an aluminium panel. You can buy different tensile strengths of aluminium panel and so you can design to minimise damage from impacts. Auminium can be patched easy (in the field or workshop although cosmetics suffer somewhat), is easy to construct and can be easily joined. Like any construction method, it should be based on good design around the materials used. You indicate the cost of sikaflex as an issue but then mention using it to also join other materials. All other methods you have indicated above have their issues either with construction duration, field repair or cosmetically over time. I have seen professionally constructed fibreglass cracking and 'crazing' after a few years. I have seen stone chips take out chunks of glass resin. I guess new space-age materials allow for a bit more impact resistence etc but every material out there will be prone to various issues on overlanding vehicles if used as intended. The side of my land rover is a testament to the ability of alumimium to withstand impacts. Sure it shows creases and dents but this is from 26 years of general farm use and offroading. Any other material would also have been damaged under the impacts inflicted.
Weight can be an issue if design is poor. If I did it all again I would use high-risk impact zones and weather tightness (sheet seam location) as the two design-related factors in deciding framing positions and the thickness (and therefore the weight) of the steel or aluminium wall of the framing material. All other areas of cladding not supported directly with structural framing would be supported by interior constructions for seats, storage and shelving that would be in there no matter what the exterior cladding. If you treat the design of the frame thus you can minimise the framing required and don't end up with something looking like a house frame. I would also use the logic that the carrier-vehicle was prone to impact damage and could be repaired so why not design the camper along the same lines instead of aiming for a bullet-proof panic-room type of safe room. Things get damaged out there, be able to fix it in the field and drive on. The ability to effect a simple field repair and to drive a camper designed for the purpose of providing shelter from the storms is what I liked about what I had and would be seeking to replicate if building today.
Flexibility can be included in the design or can be excluded as required. Aluminium can 'warp' to take up flexing whereas I see other construction methods and materials could also have problems if not designed for. If flexibilityis excessive then the seams can be under stress and again, good design is your friend.
One problem that I had that you don't mention is thermal bridging. This was an issue that I found in my house trucks and buses over the years when in very cold environments. It can be designed out if careful consideration is given.
Would I camp in the same sort of thing these days? Difficult to say. In all honesty, for ease of construction and durability in the environment I drive into for my current camping, most likely yes. As in all cases related to individual choice, your mileage may vary.
I am not saying don't build with anything else but aluminium cladding and steel or aluminium framing. What I am trying to say is don't write off aluminium as a building material for the reasons you have given.
I look forward to continued discussion and wish you all the best in your eventual choices and ensuing camping/overlanding.
"Good roads lead to bad fishing".
Eric Wight, Maine game warden