I think I'm fooked

What you can't see inside the frame would be of more concern. I would look for a frame and tub and go from there. You might be chasing rust and rot issues and in the end still not be ahead.
 
The frame having a single hole means that you should replace the entire length of both sides or the entire frame itself. I swapped my entire frame due to "one hole". The frame rots from the inside out so a single hole just means most of the frame has internal rust issues.

I would still replace the entire tub even considering the costs.
+1. It sucks getting this kind of information, but you have a rotten tub and a rotten frame. I guarantee—*guarantee*—the rest of your frame between the rear control arms and the skid plate is completely rotten. You'll need to pay ~$800 for full-length Safe T Caps on both sides. That means cutting off the bottom half of the frame and welding on the caps. Can you do that yourself? It's great if you can, but we're talking how many hours to fix both the tub and the frame?

I would sell or part out and start over again with a Tj sourced from a rust-free area.
 
I just replaced my drivers floor panel, but it wasn't in nearly that bad a shape. Well, I mean, it was, but it was just the panel itself, and it didn't extend to my roll bar mount and my torque box was just fine.

New panels aren't all that bad - here's a set of 4 for $230 - they are high quality and fit like a glove (want to guess what I used?). They sell them individually as well, along with the torque boxes if you need them. The issue comes when your rust extends beyond the panel itself. With enough time you can fix anything, as noted, but it will get expensive quickly.

I don't weld. I used 3M panel adhesive and stainless, closed pop rivets to hold it all in place. Just adding that panel made my TJ much more solid than it was. You don't need to go that way since you MiG, but for those who don't, it is a full day job, but any idiot (like me) can do it with a grinder, pop rivets, and adhesive.

Doug