For long term sailboats in Brewers the DPNR will come out and explain FAA restrictions and tell you to move along. The permanent moorings are for UVI power vessels and a couple of grandfathered in commercial fishing vessels. For a few nights I'm not aware of any unwanted attention from the authorities. Please do aim for the obvious sandy areas in about 20' of water and try to avoid the healthy coral out from the UVI Marine Science dock (good snorkeling there).