Has anybody had any experience replacing rusty floor sections with premade panels or sheet metal patches attached with panel adhesive? It's used by car manufacturers in most new cars to replace welding.

This question comes up every 6 months or so. Our cars are not new cars. Really should be welded like originally done. Your going to have to fabricate pieces to fit the rusty sections anyway. If you just glue in all the little pieces it will look like paper mache'

I can see trying to get by with adhesive on a cosmetic panel, like a fender patch, but for anything structural like floors they must be welded as designed.

I often think this comes from peeps hoping to get around the expence of a welder.
Personally if you plan to fab steel, even for seemingly minor projects and repairs, a MIG welder and a small gas bottle is the best tool investment you will ever make.

Some of the china welders (Everlast, Longevity which BTW is Eastwood, etc) have come a long way and are a damn good buy for a hobbiest.

Mark speaks the truth! I got a 110v Century MIG 25 years ago, and it's paid for itself two or three times.

You are asking for advice, so here's mine. IMHO we have eclipsed the day of using a piece of a Cadillac hood to fix a 914 floor pan, or whatever home fabricated patch. These cars are on a trajectory to significantly appreciate in the next 5 -10 years, and trying to save a few bucks today could cost in the long run. That said, it's your car and you should proceed as you see fit.

In the FWIW department, there was a 70's Cadillac hood that had a step that lined up pretty good for a 914 floor pan patch.

No

Love my Eastwood - infinite adjustability and it burns everything I've put it to so far including 1/4 inch. Damn good for the money!