On bareboats, captains are trained to make themselves scarce when they are not wanted around. Often, if you let them know they are not particularly needed (wanted), they will go ashore and not return until it is time for them to head off to bed, giving you as much space as you wish.

Having said that, you could arrange for a few nights that your captain go home and come back the next morning, provided you are in some bay on Tortola or Beef Island that is. If you give them enough cab fare, they will be happy to go home and sleep in their own bed.