A rental car for 6, + luggage and provisions -- no need to do that all in one trip, send 1 or 2 people on the provision run.Maybe CostUless was the provisioning mentioned? good for large crew and long charters especially on beverages by the case. Plenty of smaller ,reasonable size packaging on food and meats.
Call CYOA for Frenchtown mooring info - plenty of great restaurant choices in Frenchtown, not much on Water Island, Pueblo near Crown Bay Marina is a worthwhile provisioning option.
Maybe call Island Yachts for mooring in Red Hook.
Magens Bay - Brewers Bay - Buck Island - Christmas Cove - Vessup Bay[Red Hook] are all worth considering in STT. You may not be interested in shopping but the restaurants in Frenchtown, Yacht Haven Grand or Havensight are all accessible from the Charlotte Amalie harbor and a dinghy. Red Hook has good dining choices, and provisioning at Moes, The Benner BayLagoon has Independent Boatyard --and Carigas for dining and Foodtown for provisioning.
There are some nice moorings in the Pillsbury sound islands in reasonable settled weather.
The Hike from Leinster Bay up to the ruins or farther is a good one, Cinnamon Bay is a nice one, Ameica Hill is a good one , Rams Head from salt Pond is awesome, the trails out of Lameshur are very nice too.

Feet, Fins and Four Wheel Drive by Pam Gaffin is the Answer to exploring STJ - available used - ISBN 978-0-9631060-9-4