I usually climb back on from the front beam using the dolphin striker. The rear beam is lower to the water, but the rudder assembly can get in the way. I've climbed up over the side a couple of times by grabbing the trapeze handle, but this isn't possible in most conditions. I'm also a strong swimmer and still "relatively" young and nimble. I'm pretty full of myself, ain't I?
I think I saw a post from Rick or Mary that mentioned having a line with some warps tied into it that you could use as a step.
Here's another idea...
Tie about 6-8 feet of line in a loop around the mast base and thread a 6-inch section of 1/2-inch PVC pipe on it as a step. Tie some figure-8 knots to keep the PVC pipe steady and Shazam! you have a step. It should hang about a foot below the waterline when deployed. You could stow it with your righting line when not in use.

-Rob V.
Nacra 5.2
Panama City