Barton Springs Pool in Austin allows topless sunbathing. Hippie Hollow on Lake Travis is a clothing optional state park. In Texas. go fig.
I also found a web site called
TopFree that may offer some resources for anyone so inclined.Google produced a
thread from there related to good old Barton Springs. No info on Puerto Rico on TopFree's site.
Google did have a few promising leads though.
good luck, and have a good trip, whether you end up with tan lines or no.
-SWise (top on)