I was brainstorming and came up with a potentially workable divisional structure for the SEC + Missouri. I don't think it's under serious consideration but I'll throw it out there (teams listed across from their protected crossover games):
North -------------- South
Alabama ----------- Mississippi State
Auburn ------------ Georgia
Tennessee --------- Florida
Vanderbilt --------- Mississippi
Kentucky ---------- LSU
Arkansas ---------- Texas A&M
Missouri ----------- South Carolina
Major rivalries preserved, competitive balance maintained, and an interesting new "Battle of the Columbias" created between Missouri and South Carolina. I don't know how teams would feel about Texas A&M and Florida in the same division (recruiting purposes). Considering they've dealt with the East teams having a "Florida advantage" for years I don't think it will be much of a concern.
There's too much movement going on there but I like what you came up with for the divisions. There are only 5 must-save-at-all-cost division games in the SEC: Tennessee/Alabama, Alabama/Auburn, Georgia/Florida/Mississippi/Mississippi St., and Auburn/Georgia. Tennessee vs Kentucky and Tennessee vs Vandy can also be tossed in.
In your scenario all rivalries are maintained. However, I would make LSU's permanent rival to be Alabama. That really is the only change to make.
All in all, though, it's one of the more innovated division alignments I've seen.