What about South Carolina?

[Badger]

In a large enough wave, South Carolina is possible, but it's pretty inelastic, so Hillary would have to win Independents overwhelmingly, and many Republicans would have to stay home or vote for Johnson.

This. I think what makes SC so difficult for a Dem breakthrough is it's one of the few states beyond NH and OK where the urban areas tend to be more Republican than usual. (or at least the urban counties).