So D had a good idea, go-carts. Then she remembered that it has to be non-motorized. So I think a possible answer is sailboat-go-carts.
And prostitution & cocaine.
Next option: Confirm that Jimmy Hoffa is buried in the parking lot and sell of the rights to dig 6x6 foot segments. When did Hoffa disappear btw?
Explosions are always fun.
Honestly it's a parking lot. An old one at that. How are you going to make much money for the state off that? Best case you pay the salary of the ranger you had to hire to patrol it. Worst case you hire a ranger to patrol an empty hunk of pavement.