I am also in Cumming and belong to two, neither necessarily local.
Warner Robins Jeep Club - Great group, obviously not local.
Georgia Trail Riders - Another great group of people. Quite a few from Cumming, Canton area.
Most of the rides I do are out of State Off Road Parks so proximity of the club is not as important except for local Meet and Greets and such. There are also multiple Facebook Groups for Jeepers.
I guess it depends on what you are looking for.