I don't have many answers for you, but I do have a little. I had a similar situation. A shop in Hope Mills, NC, that I paid to install a new DS front pan, did cut out the old pan, and then, leaving about 2-3 inches overlap, welded the new pan in place. This might have worked, but what I didn't realize until much later was that the new pan is about half an inch higher, and it's not sealed to the torsion crossmember.
I have been told that the labor of removing this screwed up panel and fixing it will be more than the cost of getting another panel.