A 3 night charter out of St Thomas is going to be time compressed if you go to the BVI. If you can find a 3 day charter in the USVI spend it going around St John. I suspect however you will find three nights difficult to book as the turnaround costs for the boat eat any potential profit. It’s always worth trying because you might fit a hole in a boats charter schedule perfectly. Expect to pay extra however over the normal daily rate.