How would you raise the main in the water? When I raise or lower mine I have to be standing well in front of the tramp to get the bead on the halyard over the pulley and in and out of its clip. It has occurred to me to address this...I don't think it would be too hard to design a some other mechanism for holding the sail up that could be released and engaged from the tramp. This would also allow for reefing or dropping the sail on the water. I wonder if it has already been done.
It has been done. It's all a matter of technique. Racers will drop sails on the water to adjust batten tension, or fix a loose batten. Raising the sail again on the water isn't particularly hard if your equipment works the way is should (bolt rope lubed, etc.). If you need to get further out, just sit on the hull with your legs dangling in the water, facing aft.