If it wasn't for the tan and the tail she looks all Lab.
I think it is easy to assume that a black and tan medium/large size mixed breed must have Rottweiler in it. But I have to say that I don't see Rottie in her. If she was a straight Lab/Rottweiler mix, I would expect her head in particular to be more substantial than it is. Also, as someone else has mentioned, her tail isn't Lab or Rottie-like.
If I had to pick a breed that she was mixed with from the ones you listed, I would say Black and Tan Coonhound. The hound shape isn't dissimilar to a field-type Labs shape and that would also account for her colour. But then there is the tail...
Gordon Setters have that type of tail, and are obviously black and tan, but they are a fairly unusual breed. I suppose that German Shepherd could also make black and tan and produce that tail, but I don't see anything GSD-like in her apart from that.