If you build a .15 powered RC plane with a RTF weight of 28 ozs or less and 300-400 square inches of wing area the only concerns about the airfoil are about how fast you want the plane to fly.
Most old designs I've seen that made their way to publication have wings that are unnecessarily thick.
A 8-12% airfoil will produce carefree handling at all speeds if you hold the plane to the 28 oz RTF limit. You'll end up with a .15 powered plane that has excellent vertical, top speed and will land at walking speed.
A pair of 1/4"x 1/4" hard balsa spars in a 36 inch span wing that is 1" thick is all the strength a plane like this needs. I've tested .15 powered planes in this size range to the point of wing failure and 1/4" balsa spars are all you need.
1/8" balsa sheet for the fuselage's box with 1/32" or 1/64" ply doublers that extend back to the wing saddle is all that is needed, with a 1/8" ply firewall.
Keeping the weight of the model down will make all your aerodynamic concerns about the wing pretty "moot". Once you see your plane in action, it will become obvious.