I've never cleared out of the BVI in Road Town, but headed to the USVI you're likely to pass right by Sopers Hole at West End. Customs there is quick and easy (unless a ferry has arrrived, then you wait in line). Motor across the channel to Caneel Bay and pick up a ball, dinghy around to Cruz Bay to clear US customs.
When you are headed back to the BVI, simply leave the USVI, no need to check out and check back in at West End.

Someone may comment on customs in Road Town, you may be able to clear out before you start your charter.