I live in TN, which at this point has become an extension of Seattle when it comes to rain. Plus, we have a lot of mud. While rusting isnt as predominant here as, say, New England, its still something I have to consider.
Originally I thought if I were to grind down the undercoating, weld the stiffeners on, and then cover all that back up with undercoating, I'd be fine. Then I had read somewhere that you should use weld through on any auto body part, especially if its "outside" to prevent rust.
So far it seems like a mixed bag on whos primed and who hasnt. I guess that when I order the undercoating, Ill order a can of weld through to be safe. I read that "regular" primer may or may not work and I also read that using regular primer gave off fumes. I cant remember where I read that though.