Mississippi has some absolute honeyhole public land spots that open up March 15th...
but the past 3 years, the number of folks coming from Arkansas and Louisiana has been astronomical, making it nearly impossible to find a bird to work without competition from another.
You will get into birds on any of the decent sized public land or national forests in north central or southwest MS, but expect a lot of run in's with locals in certain areas. Stay away from NW Mississippi (way too many folks from both LA and AR) and SE Mississippi (too few birds to bother with for such a long drive).
I've had my eye on and done my research on the large WMA just south of Tuscaloosa, AL in case I tag out early in MS since it's only a couple hours from me. Not too many birds, but looks like a place you can get away from others if you are willing to hike a couple miles in off the roads.
In general, I would expect a ton of pressure in North Alabama and North GA from all the folks north of there coming down for the early opener. I would expect a ton of pressure in NW Mississippi from the LA, AR folks. I would think central/ south Alabama or central/ south GA or central MS would be the places to go (but again, I don't have boots on the ground knowledge of those places)