Randy I was considering just kerfing the upper (bent) parts of the foam panels , then attaching the bottoms to the floor and just bend the top part over the upper ribs, and glue ... may have to have some straps to temporarily hold the foam in contact with the ribs till the glue dries...
This one would be a much more complicated build than the little one ... but not really difficult ... I think the look and the streamlining will be worth it ... and it still should be Very light ...
Jakie , that's my plan too .... first I'll make a full size foam "former" , and use that to bend the ribs over... put those on the side till we get the floor made , then attach the formers (2) , ribs and stringers , then the foam and canvas over that ... Should be pretty simple ... much like making a boat or vintage aircraft fuselage ...
I know this is Foamie heresy , but it would be possible to put thin plywood over the framing as a skin , which would solve the inside finish question (wood interior) but then we wouldn't have all that good insulation , and it would be heavier , and subject to the problems of wood ... Maybe the plywood and the foam glued over that ... heavier though ..
Here's Swampjeep's excellent treatise on bending with kerf cuts ...
http://tnttt.com/viewtopic.php?t=44081