go 33% of your cord, and if you can keep the airfoil on your ailerons, foam wing sheeted with balsa are easy to repair, and if you do lightening holes, you can save a lot of weight..... for the fuse, use arrow shafts, if you go to a sports shop, that custom cuts them, you can get left overs, for your empenage and do the fuse with full lenght arrows..... use epoxy with a stuctural filler, so you can join and fillet arrows(stringers) to plywood..... just a thought