Memphis

We stayed at Graceland Rv directly across the street from Graceland. They have a shuttle that runs to Beale street that you catch at the Graceland Hotel. As mentioned above Beale Street is not a good area and seems like it could boil out of control at any time. (We felt much safer in Nashville and New Orleans) Parking is limited to mostly smaller vehicles and expensive.

I second the motion on Tom Sawyer. And Beale Street is not in a nice part of town.

At Tom Sawyer you get the entertainment of watching tugs & barges going up and down the river. That keeps me occupied for a few days.

As far as casinos are concerned, Missippi has a few just south of Memphis.
casino camper
As well as one in Arkansas, Casino camper ark

If your son is to the north Meeman Shelby forest state park may work.
Use caution around there in March, the area has some nasty ice storms

Tom Sawyer across the river! Best rv park in the area