Not free, but we just did this trip and stayed at Birmingham South RV park on the way down. It was easy to get to, right off the Interstate. Had pull thru spots. On the way back home we stopped just south of Nashville at a place called Texas T Campground. A very nice family owned place again, right off the highway. Easy pull thru spots.
Tracy and T
2017 Sanibel 5th wheel
2015 Dodge Ram crew cab long bed Cummins diesel