Mine were too bad to weld up, so I replaced them both. It took 8 hours for the first one, and about 4 for the second one, with the car up on a roticery. It wasn't that hard, just time consuming. If you need more details, let me know.
Engine has to be out, of course, but it could be done on the ground. It was just much easier to weld up all the spot welds while the panels were level.
I agree: if at first, welding don't succeed, then try the alternative.
Good luck!