RE: kangaroo
Well, the second wire for the retract channel is sweet, but not needed at all. You need only to disable the PMIX braking function while the gear switch is in the up position, so you didn´t waste air while flying, a good thing to do even if you have a separate air tank. About the problem of the lack of throw for the brake, presuming that your ATV on channel 7 is at 140 , you can make 2 mixes for the same channel , duplicating the servo throw. best thing to do this IMO is using a standard servo, so you could see how your mixing is working out.
Best regards, Enrique