If you have no luck with those campgrounds, I just spent 4 months at Sweetwater Creek RV Reserve in Austell, GA. It is about a half hour North of Fairburn up 92. It has full hook ups, a common building with W/D and two showers, and sometimes wireless Internet. I really did enjoy my stay there and would recommend it to anyone looking for extended stay. At the time I was there, their rates were $450 a month for 30 amp and $475 for 50.
TT 2013 FR V Lite WIKSS
TV 2013 Chevy 2500 Crew Cab