Thanks for the reply. As you mention, a day or two without being rented would definitely swing it more in the car owners favor. Perhaps the best idea is just to bring a car so ugly no one would rent it!
I tried to bring my 95' Camry with broken door handles, windows that don't go down, oil leak, and no paint on the hood to rent with FlightCar ... but it didn't qualify. Not surprisingly, they have quality standards :-p