Fixing holes in the floor without buying floor pans

I've been doing bodywork for some 30 odd years i always make my own panels but floor pans are a ***** to fabricate.like 72 scamp said the rust will be more then the patch panel.here's a couple pic's of my pan i did last winter i fabed it and butt welded it in.
I would look for a rust free southern pan.just my opinion.
keep us posted on your build.