Another work around, which is more relaxing and predicatable, is to just take a taxi with your luggage from the airport to destination, and later on pick up your rental car at an in town location. I’ve done this arriving at MIA, took $30 taxi to MB destination, then while DW unpacks I strolled over to the car rental location at Collins and 43rd Street to pick up the car. You can even save money if you don’t need the car on the first and/or last day, or if you drop it off before Shabbos and leave Sunday morning.
This avoids shlepping your luggage back and forth on that major trek between the MIA terminals and car rental center.