I think the original post is an example of me knowing what I meant but not wording it correctly in order to convey my idea fully.
my thought was to build the skeleton from 80-20, and then as mentioned, sheath it in perhaps 6 mm marine plywood. to that would be bonded aluminum skin. I have woodworking experience and carbide tools, so the method of attachment so it wouldn't oilcan would be my challenge. the space in between the framing (80-20) inside would be thinsulated, and a finished wall panel applied. also have not found a convincing argument why the interior paneling could not extend to the truck bed, and the bed sides be insulated with custom crafted thinsulate bolsters.and following that, why couldn't the floor be attached to the side paneling and - hey! - we just made a camper!!!
fiberglass could cover instead of aluminum, but I honestly don't want the process in my future if I can avoid it. and doubt gel-coating a satisfactory finish is within my skill-set anyway.
the reason behind custom fabrication (really don't like the moniker "home-made" - never have/ never will) is so that I can build what suits me without the compromise of manufacturer constraints, or financial burden for changes. lord knows I have no qualms about p*ss*ng away money, but I want to know where it's going.
I like the go-fast idea, and definitely would want the cap to bump over the truck cab a portion, anyway. I would most likely have a rack, escape hatch, solar, as long as i'm dreaming, on the roof, but no need for the tilt up feature. I was thinking along the lines of a monitor roof like the old trolleys: