Note that you've got quite a climb up (including steps) from Amicalola --- that part alone, coming at the very start of the trip demoralizes some would-be thru-hikers!

Thus my personal preference would be to keep it light. While I don't remember details of every shelter along the AT, a whole lot of them feature a picnic table. If you don't need back support when sitting, and if the trail isn't super crowded when you go (so that you can, in fact, sit at the picnic table), you've got that. A picnic table can seem like a surprisingly nice luxury when you're on trail a lot, I and others have been known to hike a little out of our way to have a snack or a meal at one.

If you do want back support when sitting, my favorite way to eat on the AT is with my back up against a wall in a shelter. If the weather is bad, it can be worth going a few tenths of a mile off trail to a shelter to eat a dry lunch along the way.
For this to be comfortable, you need nothing more than whatever padding you plan to sleep on at night, though if that's an inflatable-only solution, you might find it a bit of a PITA for eating lunch. I typically have an inflatable plus a fairly small closed-cell foam seat pad strapped on top of my pack for just that sort of thing.

Have a great time hiking in Georgia!