The only commerical camping I'm aware of is http://www.virginislandscampground.com/
I have seen a not-for-profit group tent-camp on the south-west corner of Honeymoon Beach after reserving and getting permission to do so. Sprat Bay Beach - all access is private except from the water. Water Island is a small, close-knit community and the residents keep a close eye on activities including "unofficial" camping.