I am an airline pilot and was previously based in Puerto Rico for 5 years. Our airline flew nearly all the island in the Caribbean. I lived in Ft. Lauderdale Florida and commuted from either Miami or Ft. Lauderdale Fl. every week. From any flight originating from the US to Puerto Rico or Puerto Rico to the US you will NOT pass through any checkpoints of customs or immigration. However there is on occasion an immigration officer that sits just inside the airport security screening area in Puerto Rico at least on the 2 screening areas for American Airlines. I can not remember ever entering the screening area for other airlines so I can not say for those areas. I cannot give you an exact percentage of passengers checked but it is extremely rare for them to look at any documents. I have passed through that security with passengers countless times and maybe 1 or 2 times in 5 years did I ever see them talking with a passenger. I frequently was out of uniform going through security and I was not checked even once. It could have simply been a passenger had a question for the officer. However if I were you I would contact the airline you would be flying on to verify what documents you need for check in. The airline could and might check your passport and visa and the airline could cause you problems. Now any flight originating from the US to USVI you will NOT pass through any customs or immigration. However on the return from the USVI there is US immigration checkpoint prior to being able to proceed to the boarding area. I cannot answer if the officers at this checkpoint would allow you to pass. However if you choose Puerto Rico you can rest assured that there will be no immigration checkpoints and would only have to worry about the airline restricting your travel. Good luck and hope this helped.
Marcela&Marc got a reaction from taramarabobara in Honeymoon "outside" the US after immigrating with K1 visa