I have SKID_STEER_IN set to "1" for my dual motor boat which responds to the throttle and roll (Channel 1 & 3) inputs from my transmitter.
I would prefer that it responds to throttle and pitch (Channels 3 & 2).
I'm using APM Rover 3.1.0.
im doing similar project too, i could get pixhawk to respond to my transmitter input. do you know what are the steps to make it work?