Not sure how that would work. The two units look (on paper that is) pretty similar, and on opposite sides of the shift cover. Both look to have recessed areas beneath the links that rotate the shifting shafts. So far only the right side has the problem.
I think I need to take another look at the tractor with all this in mind. Maybe pull some of the tinware off around it and see what I can come up with. If there is in fact an area down there below the lever pivot point that does not directly drain into the transmission, then it must also not get much oil FROM the transmission either. It might be possible to drill a small hole near the bottom so whatever water is trapped in there can drain out once it thaws. Might be easier and faster than trying to loosen the bolts holding the bottom cover. We'll se.