If someone is trying to get to Key Largo, (groovin to Kokomo ) MIA probably would be the best airport IMHO to get there... however, if someone doesn't mind flying on a Cessna Caravan there is seasonal air service on CO carrier Cape Air from RSW to MTH... (I almost flew this... but I would not have been eligible for any AS miles )

MTH does also have several car companies for the couple flights a day. I recall seeing Thrifty there in March, and I think Budget was there too... but not certain. Depending on how far down the Keys the OP wanted to go... MTH could be a good entry point (not sure how long until the roadwork is done)...