On the Fox, a friend of mine Steve Lang (aka "Surfimp") had a Fox from S2g and he had a hard time getting the pushrod to move the raked-back fin with any accuracy. I think he ended up with a servo in the fin in the end.

The small size of that thing might complicate things however. A 225 may be too thick. Measure, and maybe make a dry-fit test. If I was to take a guess I'd bet youre going to be forced into an HS-81 MG due to size.