Sail BVI Charter
We just got back from a charter Dec 8-16th. The place is typicaly empty between Thanksgiving and the week before Xmas when the rates go up. To me, this is the best time to go. For example, only 6 boats at Anagoda, 5 boats at Foxy's anchorage. Lot of empty mooring balls, no problem at the Baths either.
If you fly into St Tom, you can taxi to Redhook, and catch the ferry over to Tortolla.
Highly suggest you do your own provisioning in Road Harbor, Tortolla, - groceries are right near boats, and it's pretty easy.
I would worry about the size of the boat handling the seas, while bigger is better, it's more dependant on the skill or the operator. I think my wife would agree with that too.