When we visited Shiloh we stayed at Pickwick Landing State Park in Tennessee. I must admit that this was not an RV trip and we stayed in the very elaborate (for a state park) lodge, but we did drive through the campground, though that was only a superficial view, but that is where I'd probably stay in an RV for a visit to Shiloh.
We stayed at the KOA South for a visit to Chickamagua for a reenactment several years ago. It is, of course, in North Georgia and convenient to the Battlefield.
I think we have stayed in every RV park in Vicksburg--except the Battlefield RV Park: Ameristar only for an overnight, just a place to park and a good breakfast. Magnolia was OK for us. It is just across the freeway from where my Great Grandpa defended the line from the south. As I recall River Town was new when we first stayed there, a bit further out Highway 61. We enjoy staying out at Edwards at the Askew Landing RV Park in a decidedly rural setting. It is just off I-20 East.
At Savannah we enjoyed staying out at Skidaway Island State Park. We found it easy to get into town by relatively uncrowded, wide freeways.
Sounds like a great trip you have planned. Best wishes.
