2 cents, you should go with forest service trails, you can ride and camp on the roads north of Amicalola falls, Winding Stair gap, hawk mountain etc... very nice areas Other Forest Service road areas to look into include Trey Mountain and Charlie's Creek but there are a few spots here and there you may want to have a winch/come-along incase you get stuck. Personally with even with a rock capable jeep would not go out alone without straps, hi lift jack, spare tire, radio and tools just in case. And boots and a gun to make a long walk, if required. I've gone exploring several times a year for years and you can get into totally unmaintained, narrow, rocky areas rapidly.
The regional ORV parks include Morris, Adventure ORV, Chocco, Durhamtown, and Gulches. THis group can handle alot of what those parks have to offer with various levels of modified Jeeps and Toyotas. Stock Wranglers can do the easy and some medium trails at those parks. You may want to look at Durhamtown but honestly north GA is nicer unless you want to do some mudding.