Doing the same thing to my 83 Dolphin right now. Just got the bed floor out today,hope to start replacing wood tomorrow. One thing I will say is they sure made it hard to work on. Some stuff screwed in from out side and some not. Thinking of using 1/2 inch ground contact ply for the floor with a 1/4 ply on top. Will also cut the ground ply into 1x2 strips. Do know I will be mounting the windows from the outside can see why they all leak with just the inside trim holding them in place. Have posted photos on the Yahoo group http://groups.yahoo.com/group/toyota-campers/photos/album/1438235775/pic/list
will update with today destruction photos.
After starting on this sure wish I had not had to sell my Ultravan much better design and build
rich