I have an old steel bottomed car hauler that is about 25 years old. The old paint that came on it is basically missing. It's sort of a rusty color now. I am needing to do some long overdue maint. on it and I need to paint it. It lives outside, so no cover at this time. I don't wanna spend a grand on automotive paint. Does anyone have any real life experience with implement paint or something else that will last another 20 years? I plan on sand blasting it and then shooting it. I would really prefer to not primer it, just due to cost, but I understand the need for it. Any recommendations?