In real life, at my day job, I use AutoDesk Inventor software for 3D modeling, and creating mechanical drawings (shop fab, system diagrams and piping installations, facilities improvements, etc.). Each year AutoDesk holds a big convention and streams several seminars about what's new in the industry and what the future looks like for designers, builders, innovators, connectivity, graphic arts, etc.; many of these are presented by customers doing interesting things with their products.
I have been checking in on this years convention, AutoDesk University, and stumbled across a presentation where a women is making lamp shades using organic waste fibers (corn husks, hemp, seed chaff, etc.) combined with mushroom mycelium (the fibrous part of a certain type of mushroom that grows rapidly and expands). Apparently this is becoming a more common method of making molded biodegradable packaging material (essentially the organic equivalent to reinforced Styrofoam).
What the heck, why not build a two part camper mold, fill it with this stuff, and "grow" a monocoque shell? You would have to figure out a way to do the post heat to sterilize the growth process, but I figure if this can't be done with a makeshift oven (assuming low temps are all that is needed) I'm sure a deal could be made with a powder coating business that had an oven large enough.
Then I would think it's gripper and paint, no canvas needed! (Edit: okay, maybe canvas would be needed for long term durability.)
Here's the link to the presentation, it runs from about the 5:00min mark to about 13:45min: http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2015/class-detail/11913#chapter=0