RE: Biplane aileron setup
The Multiplex Evo 9 TX I am using is very flexible. You can create any mixer you want . The programming is a bit different from Futaba but once you get the hang of it , it is fabulous.
I will assemble the Plane at the field . Twin elev servos are no problem with this TX. I do it all the time .
It looks like Y top wing and Y bottom wing is the easiest .