I'm with CASO on the overlapped areas. I'd clean them up best as possible, then soak them with Rustoleum, getting it into the overlapped spots as deep as you can. The fenders came with a doubler plate where the running boards mount. That may be what you're seeing there rather than a patch. Unless you want to cut out the rust and butt weld in new patch panels, I'd use the Rustoleum approach. I looked at your pics again, and I might OA gas weld up those few cracks around the mounting holes to keep them from growing. The nice thing about OA gas welding is you don't need to get the metal spotless before welding.
