Chris,
If you are good at sketching out things, you might be able to use a rigid pushrod to use the CF on the inboard wheel/strut ass'y to overcome the opposing CF on the outboard wheel/strut ass'y -presuming 'cross y'r heart' inward retracting mains.
If you have a reference to hand, look over the way the old Goldberg retracts worked. CG had a compensating spring that gained leverage as the weight of the wheels came to bear. Set up correctly, there was little, if any, change in the torque load on the servo. By mocking that up, with the wingspan direction placed vertical, outboard down (to represent worst case CF) you should find a system that can operate on a standard RC servo.
I did, in 1969 or so, for a stunter. Servos were not as strong, back then. I added a further step-down gear to a World Engines (what, S-14 ?) servo, more for realistic cycle time than for power. Voltage was from a Polaroid camera light meter cell - 4.5V nominal, and the size of an AA cell - 9V battery snap cap ends. Got over a hundred cycles of the gear out of a cell - lost count while it still functioned...
Total weight penalty on a kit-bashed green box Nobler was less than 4 oz. Looked COOL in flight with the wheels tucked away! Since Nobler planform, etc., resembled the pre-war French Dewoitine 520 fighter, that is how the fuse was bashed, and where the markings came from. It had an ignominious end... Trippng 'gear up' took an over-control UP move, and 'gear down' took an over-control DOWN move. (Circuit like a two-switch hallway ON/OFF light setup, with a mechanical feedback center-off at full UP or DOWN.) Got a too rich flight, requiring whole bunches of handle motion to get a sharp enough turn to hit the switch limits. Hooked the down line over the handle trying to extend gear. Went straight into a muddy field, to the wing roots. THEN - wheep-click, the gear came down and locked...
THAT shouldn't be a problem with a scale ship...