I would add two additional sub-regions to your list:
1. The Mid-South. This would be the area that includes Nashville at its center up toward Louisville and west toward Springfield and Tulsa encompassing the Ozarks. This is the border between the Midwest and the rest of the South, with elements of Midwestern and Appalachia culture. This also encompasses the industrial areas of northern Alabama and Mississippi.
https://www.nwtf.org/about/big-six/mid-south
2. The Southern Piedmont. Different than the Deep South and more historical Tidewater areas along the coast, the Piedmont is a rapidly growing area with an increasingly industrial economy. This includes cities like Charlotte, Raleigh, Durham and Greenville. The culture is a blend of Appalachia and Deep South but with more Mid-Atlantic influence. Atlanta is at the edge of this region where it turns into the Deep South.
https://www.researchgate.net/figure/...fig1_271910023