Oh happy days. This argument brings back many happy memories of my time in PR
from 1999 to 2003 and a short time in 2005. I will stay out of this little discussion as I don't have a decent rum in my hand.
Unless the situation has changed, on arriving from the USVI's the best check in was in Culebra. Anchor your boat, dinghy ashore, walk to the airport where they were friendly and efficient, walk back have breakfast/lunch/start drinking. Job done.
The reason for the check in was, as stated, the USVI's are Duty free, PR