Man I will say there is no way a Southern Jeep has rotted that bad just from the Ga climate. That thing spent time up north guaranteed. I live north of Atlanta in Roswell and my 97 doesn't even begin to have rust like that. I have worked on dozens of XJs and the only ones even 1/8 as bad as that spent part of their lives in the North.
I have a buddy who is Southern and stubborn much like you and his XJ was rolled going 55 mph. The roof is caved in, the windshield frame is trashed, the front passenger side and "frame rail" completely crushed, and the front axle bent severely. He claims he is going to turn it into a buggy. He doesn't have the time, space, skills, tools, or money to pay for those things nor money to pay someone else to do it. Its been sitting for two years in his gf's garage and her patience is growing very thin. He even has another XJ now that he can used the salvaged parts from and let his old XJ live on in this new one. He would be much better served saying goodbye, saving what he could, and building his new one with the money he gets from scraping the old one.
I understand your attachment to your XJ. I have had mine for 11 1/2 years. My first XJ and the Jeep I learned everything I know about cars on. I have so much blood, sweat, and tears in this thing to ever just toss it without a care. I could never sell it and it would kill me to scrap it if something happened to it. But I would also be realistic. I would be better served salvaging what I could and saying goodbye. I would buy another one and let parts of the old one live on in the new Jeep.
I too like to fix rather than replace but you have to be realistic here. So much of that thing is rotten that you will be trying to weld to rot. Even if you manage to clean up some of that, you will be welding to metal that is now even thinner because the surface has rusted away so much.
I am not trying to be negative but you need to let that old Jeep retire. She served you well but its time to let the old girl go. Trying to fix it with your skill level could be dangerous no matter how careful you are. This would be a really big job even for a master fabricator. Southern Pride can be a blessing and a curse, in this situation its your curse.