do you have the rust controlled right now? ie.. sanded off.. wire wheeled off.. sand blasted off?
if so.. for 100$ you can buy a cheap paint gun.. a gllon of alkyd enamil, a gallon of primer and a couple gallons of naptha.
you can shoot the primer and then paint it. have a day or 2 tied up in it. it will then be sealed and protected from rust well enough to use. later on you can refinish better.