Hoop, if you are down-bound from the States to the Islands, you do not have anything to do with customs or Immigration in SJU. You will claim your bags and head to the proper terminal. The 2:30 flight would DEFINITELY be doable if you weren't waiting for baggage claim, but with the 5 PM flight you are totally covered.

There is nothing to stress about in this situation. Getting Lucky would mean your bags are quick, and you get to Air Sunshine in time for the 2:30, but I wouldn't be tempted to hoof it unless you incoming flight arrives early and your bag retrieval is FAST. Otherwise, just go check in with AS and then unlimber your wallet for lunch and a few beverages.