Whatever you do Do Not miss Natchez and Vicksburg MS. They are really lovely towns with tons of history and in beautiful spots with great RV Parks. The old Plantation homes and their checkered histories are must sees.
A real eye opener and a very nice small museum is the Natchez Museum of African American Culture.
Tour the Vicksburg Battle National Military Park. It's moving and gives one a real sense of the battle lines and troops who fought here. Do not miss the USS Cairo Museum which is part of the Park. It's a stunning piece of 19th century technology and a fine museum.
Between Vicksburg and Natchez is the Grand Gulf Military State Park a civil war era site and museum with it's own campground which is very very nice. This is a peaceful and beautiful place to stay.
Back to Natchez There is a very nice RV Park River View RV Park just across the Mississippi from town in Vidalia Louisiana. It is right on the river with a view of Natchez.
And any trip down the Miss must include a stop in Memphis and, yes hold that derisive laughter...a visit to Graceland. Now I am fully aware of what some perceive of this place but I can tell you that it is a very educational, and at times funny and moving experience. Dont miss it. And there are two RV parks just blocks away.
Suspend your judgement on that and just go. You wont regret it.
Finally in New Orleans the National WWII museum is one of the finest in the country if not the best. It personalizes this titanic conflict with immediacy, empathy and in great detail...very well done. Don't miss it.
And last but not least is the New Orleans Museum of Art. Plenty of Old Masters, impressionists and more modern art a very worthwhile stop.