If you are keeping the cab dry in a garage, the other option is to use phosphoric acid on the bare metal. The phosphoric acid (brands such as Ospho) are misted on with a pump up sprayer, scuffed with a scuff pad, then wiped with a paper towel. The surface of the metal won't rust after this application unless it gets wet. When you are ready to primer or bondo, you scuff the surface with scuff pad or sand paper before cleaning and priming or bondoing.
One caveat with using phosphoric acid is not to use an etch primer or epoxy that contains acid when you coat it, otherwise you can have delamination issues.
I live in New Orleans with high humidity and this still works well for me for parts that are stripped and in the garage waiting final body work and paint.
I hope this is helpful.
Regards,
Steve
New Orleans
