The water leak through the sunroof isn't that big of a deal. Pull the headliner, replace the gasket. The previous owner of my car fixed it on mine before I got it. I was lucky
I'm not talking about on the outside of the weld. On the other side, it is in a frame rail, so it's not the easiest thing to get to. I have a "corrosion protection spray gun" at my shop in UT that can reach back inside frame rails.
I'm trying to fabricate a bolt on piece. The metal is pretty weak so there isn't a good place to tap either. I could weld em on, but i'd rather not... I don't have any corrosion protection I could use at the moment.