RE: Bob Cat Copy Falcon 120 Jet
If you put the rudder servos on separate channels, you will be able to fine tune the trim over time, shouldnt be an issue. I have seen many full sc ale jets get bent minutely. Should not be an issue. The challenge with twin rudders if trimming them relative to each other while still maintaining no fuselage sideslip because the forces will offset each other. An extreme example is lets say one rudder is deflected 5 degrees the other is zero. The plane will still be able to be trimmed for zero yaw, but the rudders will both be deflected opposite each other, likely in a proportional amount. THen you can individually trim them back to zero incidence and try again to retrim in flight. Keep at it, and by individually recentering a few times, you in effect trim out the differences in the airfoil, and imperfections. The jet will find equalibrium by using your rudder trim. I see this in ailerons all the time. Once its trimmed, look at the surfaces and retrim them for equalibrium. then try again. Its really easy to do with separate channels, just like flaperons. Just remember the linkages should be as identical as possible for perfect proportions.
Once trimmed, you have minimized drag as well by finding the least drag position that produces zero sideslip.
hope that helps