For these loads, I doubt you'd need ball bearings. A simple brass-in-brass bearing would work: K&E brass tubing, available at hobby store or (hardware/lumber stores in Bozeman), is sized to nest. Pick a size tube big enough to fit the foot of your mast (shave wood down as necessary). Then pick a tube the next size bigger. Glue the bigger tube to the keel and let dry. Slip the tubed mast into the "bearing". By using the nested tubes you get a good bearing, and you also guard against the wood swelling when it gets wet. add another bearing at deck level, and you are good to go. The deck bearing could just be the bigger tube, it's function is to absorb the leverage of the mast when the sails fill. Best would be the double brass bearing as at the foot, but you could probably get away with the simpler single brass setup at the deck.
Modifying the tx is not hard, but if you don't want to, no problem, you'll just find yourself holding the sticks over in one corner or the other as you sail. Been there done that, it's certainly feasible. On the other hand, I've never had a tx that would ignore the sticks, if you can make it work, cool.
I know you are set on rotating the masts, but really, if you get fed up with that scheme, the simple parallelogram method (pioneered by Phillip of Steele, Hutchinson, etc.) works fine and is pretty simple to setup with standard servos. See my BottleBaltimore thread. I'll be happy to answer any questions you have.