I didn't think to mention this, but some of the guys at our club use pvc rollers. That is, they have 5 or 6 sections of 3" pvc pipe and roll their boats up the beach like the Egyptians did the big stones. You have to keep taking the one out from under the rear and putting it under the front of the boat. May not be a good idea, if your ramp is very steep.

Just another thought,
David