There are plenty motor
yachts, many smaller than 48', in the USVI, Spanish Virgins, and BVI. Also in St. Maarten. They become fewer as you move down the island chain, for whatever reason. Probably due to personal choice of cruising grounds, I suspect.
It's relatively easy to find good weather
for the inter-island passages, where you'd be exposed to heavier seas and winds. Conditions in the anchorages
on the lee sides of the islands are fine for power and sailing yachts.