runover 1,
You might try using a pull pull rudder system, putting the rudder servo in the throttle servo tray and moving the throttle servo forward. I did this and mounted the throttle servo on it's side. with the servo arm pointing down, with a shim to give the arm clearance. Mine balanced perfect with a Saito .72 with this set up. The OS 46 fx weighs about the same as the Saito .72 so this should work for you.