Did one a few months ago. I took me about a day from start to finish. Having a spot welder will help when bonding it to the rear 1/4 at the bottom of the trunk drop off (I think that is what it is called).
If you only have a MIG, you can still do it, but the spot welding makes it look more factory.
If you are trying to keep all of the other neighboring sheetmetal in good shape when you remove it then this is a hard panel to get out. The hardest part will be removing the metal where it is welded to the bumper support brackets. Since the taillight panel curves in it is hard to get access to that area I mentioned. For me, my rear taillight panel was in good shape but everything else was ruined - wheelhouse, quarter, etc. I can't remember exactly but I think it took a day of beating, grinding, cursing, etc to get it out.
You'll need to remove the bumper bracket. when you reinstall it, make sure you weld through the bracket and trunk floor to the frame rail, or there'll be no strength in the bumper.
The welds can be replicated by "rose welds", basically just punch 3/8" holes where the welds need to be, and weld thought them to the frame rail. If they're not flat, grind them smooth.