Hey I crash paded in Mia for years. If you go to the East side of the airport there is an apartment complex called Airport Villas.
I started my own crash pad there, the rest of the building is mostly crash pads you could find a spot in. I can't remember the north-south road that borders the airport on the east. I think it's Lajune. Anyways the villas are behind all the car rental places and a couple hotels and a restuarant called flanigans. The airport villas have an office, when I was there the manager was Juan.
It's not luxurious but served it's purpose for years. You can ride on the rental car vans to the airport.
