Need advice on shaving rear fenders

I need some advice on shaving my rear fenders. I decided its neccessary because rolling was kind of a waste of time. The fender lip is still at least 10mm wide(I'm sure it could have been rolled tighter). This weekend I was taking a long drive with my car loaded up, and I hit a big dip on a sloped road which caused the right rear to compress more than usual. The rim just barely rubbed on the inside of the fender lip and I'm going to have to get it repowdercoated. Before I do that I need to make sure it doesn't happen again though. I already sanded down about 5-6 inches near the bumper and rubbing wasn't an issue. I plan on sanding the entire lip so it's flush with the inner fender like I did by the bumper. The only thing I am worried about is that the inner fender and outer fender will separate since there will be nothing holding them together. Ideally I would weld it, but I don't plan on repainting my car anytime soon. Is there any other way to hold the inner and outter fender together like an adhesive or something?