Dream catcher,
If you only have time for one night in St John, I would suggest you don't go to St John or find a way to change your schedule so you can spend more nights there. We did the one night stay in August, there was just too much "official business" for me for a one night stay. Check out of BVI (JVD for us) check into U.S. At Cruz Bay via Dinghy, check back into BVI at Sopers.
Sorry to put a damper on your plans,
Tony