I'm not sure you can check out and back in at the same time. When visiting the BVI from the USVI for a short visit, you can check in and out at the same time, but I've never heard of out/in altogether.

I'd agree Coral Bay is not a great spot to snorkel/swim. It is an ok overnight though - we stayed last November - did dinner at Skinny Legs and watch some of the Patriots game. It is a decent spot to walk around - a prior trip we made a day stop there and walked from the dinghy dock all the way around to the other side of the bay.