I just programmed my brand new 9CAP and QQ 86" Yak last night with a 7 channel Futaba Rec. I used 2 as master and 7 as slave. Channel 7 is a primary auxiliary channel. Channel 5 is for retracts and will take more programming to use it( I used 5 for choke on the engine).
The set up you speak of is possible and the preffered method is as I set it. 2>7 using programed mix #5, but any mix will do.
Adam