On my last tj, a club member cut out parts of my floor and welded in patches. I would make a recommendation, but I don't want to volunteer anyone.
For my current tj, I bought the front stamped panels above from quadratec. They were cheap enough that it made sense. I plan to cut out the largest section of rust and trim to fit. I would volunteer myself, but 1) I am not a good welder and 2) I haven't had time to do my own project
The body mounts are a trickier one. I have never done one, but if the tub is still on the frame, you would have to cut the top side of the channel out of the body to gain access to the rusted out mount, cut and weld in a patch on the bottom side of the tub. But if you cut out a large enough section, you could possible do it from the bottom.
I can't recommend a body shop, but maybe someone in the club will be looking to take on a winter project......