Wes:

Tere are mechanical mxers on the market for Vee tails, you could use onr of them with the throttle going to the elevator input, and the rudder going to the aileron input. This would let you do it with four channels and no electronic mixing. But I think you'd be better off with no thrust differential than to do it this way.

A mecfhanical mixer can be made to allow differential thrust at part throttle only, leaving the engines synchronized at idle and full throttle. This would still not be ideal, but it would work better than the elevon mixer.

Electronic mixing is by far the best, but you'll have to have at least a five channel rig with proportional control on the fifth channel, or a six channel transmitter and receiver.

Twinman is the differential thrust man, he has made several posts abouit his methods. Do a search using "Twinman" as one word, and "Thrust" or "Throttle" as the second.

Bill.