As an old time Ringmaster owner, I'd recommend under the wing. My original had them inside. Sold that plane with a McCoy .35 in 1967 or so. It flew very well.
(A national guardsman needed something to do in his spare time at camp.) That was the last control line model I owned!
The bell crank had a ball bearing, and the McCoy a flapper throttle using a third line. (Spring loaded open)