Rear Arch Trim

Hey guys I'm just about finished getting all the rust off from the back wheel arches most of it seemed to collect around the rear wheel arch trim. Just a quick question to see if I should put this trim back on or use something like stone chip shield and underbody coat with waxoyl? I suppose the purpose of the trim was to stop stone chips, but I figure they catch water.

Yeah those damn trim pieces do catch water, and the rust does reside uner them primarily, its a bitch.

Without them they will rust too though, its just kind of a trade off.