Another alternative is to go up from Mobile, AL to Jackson, MS and pick up I-20 West. That would put you through East Texas where there are plenty of COE campgrounds not far off the Interstate. Here are a few:
Lake o' the Pines, two nice campgrounds on each side of the dam: Buckhorn and Brushy Creek. About 20 miles North of I-20
Bardwell Lake, southeast of Dallas may be a bit too far off your route, about 45 miles but there are 3 COE campgrounds around that Lake.
Benbrook Lake is just 12 miles southwest of Fort Worth and less than 10 miles off I-20. Holiday COE Park seems to be the best campground around Benbrook Lake.
I am limiting myself to those campgrounds near to I-20.
One last comment: I-20 around Dallas/Fort Worth is one of the best bypasses around an urban area. I have rarely had to slow down from posted speed limit. Of course, I may have been lucky. One wreck could create an entirely different situation. Still, I have found the traffic to flow freely on I-20 south of DFW.
You will merge with I-10 out in West Texas.
