Airplanes: Chuperosa Part 9

Structural construction is now complete. I'll be using microlite plastic covering to finish it up. One obstacle remains however, after the covering and radio install. I'm not 100% sure I have the incidence correct. I made sure the wing saddle matched the prints, but I'd like to measure to be sure, and of course I don't want to drop more cash on an incidence meter. Does anyone have an accurate way of measuring this using a straight edge or something?