People have written a great deal about Frank Okam of Lake Highlands being perhaps the top defensive tackle in the state next year. To this point, I haven't seen anything about him even considering SMU as a backup plan. In the meantime, there's another high big DT in the area who might be worth looking at:
James McClinton
Garland (Lakeview Centennial), Texas
6-1, 300, 5.2
Not sure who he's considering, of if he's even begun to narrow his choices.