I don't know if they do any rentals, but Megrew's Boats in Charlestown RI is a Hobie dealer. Flett 448 has a new website:
www.fleet448.org . There are contacts listed there, as well as a forum you could post on. You can also try Rick Bliss. He has a Performance Cat dealership in Mass., and sails in RI frequently. His contact info should be in one of the 448, or Division 12 links. He doesn't do rentals, but may put you in touch with someone to crew for. I like to think you could at least hook up to crew for somebody! When will you be up?