I think you're right. I really didn't want to use a clevis at both ends, but it looks like I better just to be safe. Why do you suggest plastic instead of metal?

By the way, the exterior of this model will be completely sheeted and naturally finished. Therefore I'm making the control horns out of plywood.

At the bottom of this page you can see the wing in it's current state. I also built up the stabilizer and will build up the fin and rudder as well.

http://www.airfieldmodels.com/wing_construction_08.htm