Generally, I don't think anyone you have direct contact with in Orlando is going to care about the origin of the car. They will simply follow whatever procedure that's in place. I'm guessing, that procedure would involve charging you more for unexpectedly breaking the contract.

Regardless, rental car companies never have any problem getting cars back to Florida. It's really the opposite. Almost all companies have special "drive out" promotions every April through June because they have a glut of cars in Florida. These promotions give very cheap rates (as low as $1/day some years) for anyone who drives the car from Florida to many major cities in the eastern third of the country.

In my opinion, this isn't going to work.