Great job! Lot's of work there. I had similar rust and used the same panel. Mine was a Key Parts piece from TriPro. I think they're out of business, though.
We chose to laminate after grinding. My truck will spend it's life (as long as I own it) inside, so I wasn't too concerned with the rust coming back.
I figured the issues were brought from the seam sealer deteriorating and allowing moisture in.
I've attached pictures of our experience.
Good luck with you restoration, BTW. I'll be following!
