And I thought I had trouble with getting the servos in a Wing Mfg and VQ P-38!!! You are putting retracts in this!!! I cannot imagine!! I am unworthy!! Have you considered mini and micro servos with metal gears and 6V? I had good luck with these type servos in the Wing P-38. Would also really suggest two servos for the elevator to avoid flutter.
Good Luck and keep us posted.
Twinman