Jeff,
Why not give corrugated cardboard a try? It's inexpensive and very strong & resilient. It doesn't crack or shatter like balsa and fiberglass, but just dents locally, and can easily be repaired. I have been designing and building cardboard models for over 30 years, so I know what it is capable of producing, like my 70" wingspan FW 190 and 60" wingspan P-51 control line models in the pics. Visit http://home.earthlink.net/~charlesfelton to see pics of construction techniques and models designs. One of the biggest advantages of cardboard is that it can be scored and folded allowing each wing half to be built from one piece of cardboard. Hows that for simple and fast construction? Check out the site to see both R/C and CL models and let me know what you think.