Not sure if you're coming in the day before. You can rent from Avis and drop it off near the port. They'll shuttle you free to the port. Then when you return, they'll pick you up at the port and bring you back to Avis. You can then rent and drop it off at the airport. What's nice is you can do stuff before heading back to the airport at your own leisure. We come in the night before and like to do stuff. Then just drop it off in the am.