I guess it depends on what you mean by "reasonably accessible" doesn't it.
Last January, my wife and I were certified USS for bareboat, by Offshore Sailing School out of The Moorings charter base in Tortola, British Virgin Islands. They also run RYA certification now at that location, apparently up to Coastal Skipper (according to their web site). http://www.offshoresailing.com/locations/b...in-islands.aspx
You might inquire as to further levels. Our instructor was a certified instructor for both RYA and USS. The Moorings, the school, and the instructor were all great.
The BVI are fantastic! Met every expectation that we ever heard/read about. Awesome conditions for sailing and snorkeling/diving. (We missed the "Christmas winds".) Very laid back, if you chose to be, or high-end if that is your liking. That was our first trip to the BVI and hopefully we will return again and again. Our only regret was not having more time after the instruction was over, to sail on our own for another week.