Wingamm make monocoque coachbuilts in small numbers, but they are expensive. I am totally in favour of a paradigm shift away from the current cottage industry business model and its inconsistent workmanship problems. Let's have lighter, stronger composite materials. As for foam as insulation it should also have low combustibility, unlike the flammable stuff inside MH panels today which spreads the fire and destroys the entire vehicle in a few minutes, so you need to get out really fast.Will be the end of pressed steel vehicles, computer laid up composites to get the weight low enough. Strength got from double skin over a foam interior like light aircraft. So ideal for a motorhome as ready insulated.