Ok ive got 2 ideas for the skin, or at least the top to make it the best waterproof.
the first idea is using linoleum, has anyone done this?
The second idea is pretty radical. My main hobby is building and flying model aircraft. They are all covered with a plastic iron on covering named Monocoat or ultracoat.
http://www.horizonhobby.com/Products/De ... ID=HANU866
http://www3.towerhobbies.com/cgi-bin/WT ... &search=Go
this stuff is 100% waterproof, is made to sit in the sun for years, is very easy to apply and repair, and would be very very lite. It would go on over plywood. What do you think?