Note - if you want to stay free, South of the Border's truck stop is likely a possibility. But, they also have an inexpensive campground that is good for overnighting (or so I've read).
We stayed at Whispering Pines RV Park in Rincon, GA on our way home this year. Nice place - about 8-10 miles off of the highway, but a pretty straight shot if you follow their signs and not my stupid GPS. The site was a pull-thru and incredibly level. Office was closed when we got there, but they had an after-hours drop money in an envelope that worked just fine.