Do you all by chance know how the diving is at the end of March?
I've never been there in March but I believe that @TN Traveler lives on St. Croix and he posted the message at the link below:
USVI Dive Vacation - what do we need to know?
My experiences in other areas of the Caribbean are that the water can be cold and the weather may be windy in winter. Places are more crowded and the prices are expensive because it is the high season - although things may be different this winter because of the pandemic, IDK.
If you could wait until after Easter and Spring Break (late April or May) you may have a better chance of warmer, calmer weather and water and cheaper prices; but there's never any guarantees about the weather - and if you really want to escape to a warmer climate in March - then go for it!