Paint will always crack if flexed. It's not a matter of if, but when. Do you have room to add wood behind the trailing edge of the wing in the aileron box? If so, do so, and use a set of dubro pinned hinges. slot the aileron, and the trailing edge, and after installing, use toothpicks through the hinge and the wood. Touch the end of the toothpicks with a drop of thin CA and sand smooth. Last, add a strip of covering material (iron on works here) to seal the aileron gap. I have used this method before where there was not enouch, "Meat", to properly install hinges. It workde well for me.

Bill, AMA 4720
WACO Brotherhood #1