Fixing holes in the floor without buying floor pans

The dart is going to need some surgery soon. Wondering what metal to buy to fix the holes in the floor. It does not have to look OE. Has anyone just cut out the bad spots and put in a patch.

I'm guessing its too far gone and new pans would probably be easier but the whole car is rusty so were do I stop!!!

Here are some pics of the drivers side floor pan.