Rust Proofing

I have an 89 suburban that spent some time in the sw so I am just beginning to get rust problems. Visiting the junkyards showed me how quickly some of them are turning to rust.

Mine was zeibarted but after looked in the rear cargo doors, the only evidence was the holes and plugs

What have some of you done to control the rust?

Anybody gone the waxoyl route?

Anyone use por15 and have tips on how to use it???