If the divots are coming from contaminants in the air you should be able to sand them level and respray and not generate more problems as long as you...
You could just mask off a section on the door and spray it black. If I were doing it I'd probably mask it from the top front to the bottom rear then...
Another thing I like is that I can lay the gun down anywhere. If I'm not next to a gun hook and I have something that needs attention I can just lay...