I've been trying to decide how to do the walls. I am thinking about 1/4" ply/extruded poly insulation, 1/4" ply in a sandwich. I may even go 1/8 ply. Glued and screwed, it should be strong and lighter than my original idea of using 1/2 ply for the sides. I have a couple of road trips to make over the next few weeks so I'll probably pick up lumber next month when things slow down.
I think I made the right decision to stick with the 1175# trailer. I pulled a big jetski with my truck last week and it didn't do as well as I would have liked. Much more and it won't be a pleasent tow at all. So... My finished product has to be light in order to work with my 4cyl S10. I almost traded it in this past week but couldn't bear the thought of getting hit with another first month depreciation on a new car so soon. Especially since I just bought the S10 back in November.