Assembly question for bodymen

I removed my fenders to paint the front end of my car and inner fender wells. Now I’m to the point of installing them and I was wondering if it would be a good idea to put something between the fender lip and where it bolts to the front end (running along the top of the fenders). My fenders have a bit of scale from along the seam where they were bolted to the car. I’ve treaded them with rust convertor and painted them with chassis paint, but not sure if I should bolt them back on as is, or put rubber insulator or foam tape or something between the seam.