There is a paint for aluminum tanks on Peterbilt fuel tanks we used to trick out. Metal-Lock (?) Lasts forever except for road chips. I had my white-out pkg on the old Fountain re-done (factory powdercoating wasn't worth a chit) and it was still new after 5 yrs. I will never powder coat anything.

I spray it with one of those mid-sized guns you'd use for touch-up or door jambs. Mine is made by SATA

Acetone is the best for removing anything- be surte that you use an automotive body-refinishing wax and grease remover first, especially if you used grease-based buffing compounds