I kept finding wet carpet after driving in the rain. This is my experience in fixing that This is what I found. Notice the seat brace at the top of the second pic. That's my foot you see where there was supposed to be sheet-metal.

 

I had four of these holes that extended past the floor. Had to patch those. Like this one. The edges were formed to fit and tacked. 1/4" at a time. The rest were plug welds.

 

I cut the cross brace off just below the seat bolt holes. Bent replacement sheet metal and welded them together.

 

The floor is welded in and undercoated. I started out trying to use .035" flux core wire. Not a good choice for sheet metal work. I ended up using .023" solid mild steel wire and a 75/25 Ar/CO2 mix gas in a mig welder with much better result. My TIG skills aren't up to the task yet. Maybe once I start on the CJ's body panels. I have more pics in my profile gallery.