That's what we are doing, going on the first flight out on Tuesday morning, at 6 am non stop to Lauderdale,and returning about 4 PM on Monday. I booked two one way rentals with no drop off charges from Alamo, $51.57 at Ft Lauderdale and $46.76 at Key West, that was using a GM discount for a mid size car.
It would be funny to finally meet you for the first time in Key West, since we live in the same town and you have driven by our house