Fixing holes in the floor without buying floor pans

It's quicker to replace the front pans than to try to patch it up, on the rear wheelhouse I would clean it up and trim back to clean metal then make a patch with 20ga steel and weld it in.

When I put the front pans in my Dart I cut around the perimeter with a sawzall then ripped them out by hand, there was rust between the rail and pan so there wasn't much holding them in, it took me a whole weekend but I had to repair the firewall and trans tunnel also, the rear pans took about 3hrs to R&R.