Back to the top of this post.
I think if you plan on Generic Foamie in the design resources tab. It should be very easy to build, low cost and look good.
Something almost anyone could build with very few tools(saber saw caulking gun and a palm sander)
I would like to see a 4x8 just because it would be so simple to build. You could put in the option to go wider and longer but the basic design for a 4x8. I like the looks of the grasshopper(weekender)
With the bottom front going strait down,
The gallery door hinged on the bottom to make a counter(or a inside fold down counter)
2" radius's on all the corners.(for a smooth look).
2" foam floor with Canvas on the bottom and a sheet of thin plywood or luan on the inside.
Glue on hard point to make building easier.
Wylie windows for low cost.
Low cost homemade all foam and canvas doors with canvas around the edges (mine are 1" foam)
No wood so no rot if there is a leak when stored outside.
If built off the trailer you can wrap the canvas under the floor with easy and have it upside down to canvas the inside of the roof
Just my thoughts.