RE: v-tail and jr xp783
I will look up my manual when I get home and look. I am pretty sure there's V-tail setup. Heck, I've set-up quad flap and Delta on this radio so far.
Going by memory, you should be able to do the following:
Plug 1 tail servo into Elevator channel
Plug the other tail servo into Rudder channel
Activate a mix selecting Elevator to Rudder
Activate another mix selecting Rudder to Elevator
Adjust the direction and travel accordingly
If I forget to respond to you, just send me a PM.