I would stay at the Downtown Riverside RV Park in Little Rock. You can access it from I-30, exit 141B, then you can exit toward I-40 and continue on your way. No campgrounds between Little Rock and Memphis that we have found. In West Memphis we like Tom Sawyers.
In Nashville we liked Two Rivers Campground. Convenient location, lowest price. Not the fanciest but we liked it for seeing the area.
Out of town to the east is Seven Points Corps of Engineers Campground. Bit of a drive to see anything but can't beat the price!
Lonny & Diane
2004 Country Coach Allure 33' "Big Blue"
Towing 2008 Chev Colorado 4x4
Semper Fi