Great build! I've been toying with the idea of using composite panels to build a camper for my truck, as well, though maybe not to the sophisticated level of your design. I think mine would be a pop-up design, too, since the truck would need to get in and out of tight trails, and I'd rather have as little height for me to forget about as possible. My family has been in fiberglass for 40 plus years, so it makes sense to go w/ fiberglass composite panels. Now that I see yours I wonder, do you sell the extrusion channels like you've used on your camper? It would definitely make joining corners much easier and retain a very "finished" look.