[Hogshooter]

I like the wire wheel and a 3M clean and strip disc to clean those tight spots followed by epoxy primer rather than the weld through primer, it is catalyzed and has better corrosion resistance properties, like the rust encapsulator. If I were you I would not spray the underside until you have welded the part in to save material. Great job so far on the skill development the lessons you have learned will serve you well installing the floor.