Thanks to everyone for all of this wise and sound advice. The prior owner I believe was slighter than me but we removed all the foam he had added. I'm not sure if maybe the seat was raised up a little bit; it was a factory seat and I think glassed in, though now not entirely sure about this. It could also be that older Explorers have a slightly tighter fit -- since it sounds like several of you are about same size and don't really have any problems with the thigh grips.
With a regular Romany, I've found I fit, though a little tightly, with a thinner foam seat but it maybe my thighs (or posterior) might be generous enough that I should look to try out a Surf and pad it out a little bit if need be.
Curious how Surfs handle in comparison to regular Romany and with Explorers -- especially for someone around my weight. I occasionally do interval training and so have found I sometimes top out the hull speed on the regular Romany, creating a pretty sizable bow wake, but of course when doing any longer trips or in rough water this wouldn't really be an issue.