Probably not even close to the worst decision ever, but not a decision to be made without evaluating your options thoroughly. T14's would give you mobility, which it seems you want. Since that's not an option now, decide where you want to live and work after law school and go to the school in that region. I don't think you can plan 2 steps ahead, there are too many variables.
Don't be upset though, SMU is a great school and Dallas is a very strong market, going to SMU for free is the complete opposite of a bad idea. It's only a bad idea if you know you don't want to work or live in Dallas.
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