Clearing customs isn't a problem we checked out at Sopers Hole it only took about 20 minutes then we checked in at St John another 20 min. If I remember correctly not everyone has to check out of BVI in person just passports are OK but in St John we all had to check in with passport in hand. And another easy check in once back to the BVI. I don't think it's worth a day trip. One observation I had was the people and facilities are not as boater friendly as in the BVI. We stayed at Cruz Bay overnight and we're not too impressed with the vibes from the people or the resident boaters