A campaign sign for Toby Doeden, a Republican candidate for governor of South Dakota. (Photo by Brad Johnson/for South Dakota Searchlight)South Dakota is being told it needs saving. Not tuning. Not reform. Saving. That word isn’t a diagnosis. It’s a marketing slogan — the kind you roll out when you need voters to believe they’re living in a disaster movie and only one man has the script. Into this imaginary smoke steps Republican governor candid…