Salt Pond Bay (north shore of Salt Island) is a fine overnight anchorage as long as you dont't have strong winds from north of East or heavy north swell forecsst to move in overnight. I can't think of anyplace in the BVI that you are forbidden to overnight anchor (except for within mooring fields and the National Park boundaries which are no-anchoring at all times).

Salt Pond Bay, St John is a wonderful and secure anchorage (mooring balls only) in virtually all conditions.