If it were me I would look at the foamie section, then build the part of the camper from the bed rails up with 2" foam. With some wood framing for the doors and windows, and roof rack mounts. Your camper shell would be super easy to heat or cool, quiet, and light weight.
Foam would also be easier to sculpt into rounded shapes to match the syling on modern trucks.
Even if you don't like the idea of foam walls and roof, you could just splice some foam in at the corners, then fiberglass over the whole top once you got the profile you wanted.
make sure you share picutures

if enough people like your build I could see this being the start of another section for tnttt! "Truckers!"
