I have some serious scuffing on my car’s door sill. I bought some black xpel film to prevent this in the future, but I want to do something to prevent rust from forming underneath the film.

I bought some color matched touch up paint, but I’m wondering if I need to remove all of the paint and primer from the area. Since I don’t care how it’ll look under the film, I’d like to just rough it up with sandpaper, prime and paint it, and then slap the film on it.

The part I’m worried about is that it’s a fairly large and irregular scuffed area. Some bits are down to metal, some down to primer, and some still has the clearcoat. I can’t really mask it off and only get primer on bare metal and the original primer.

The reason I don’t want to sand it all down is that it’s a difficult area to sand. I’m worried I’ll fuck up the paint beyond the area that would be covered by the film.

Can I do it the lazy way, or should I just bite the bullet and sand down to metal?

It’s water based touch up paint if that matters.