Rustoleum makes a fine product. Applied correctly, it can outlast you. No one has a crystal ball. I just love when the experts come out. My advice is simple. Try a small spot. Prep it like you would the whole thing. Then prime it and paint it body color. See what happens. I just "BET" it turns out fine. When it does, just do the rest and blend in with your test spot.
You COULD even try a simple degreasing and try a self etching primer and see what that does. That could eliminate the need for sanding.
