“Can anyone recommend a real estate agent who may be a good fit in helping me locate a property like the one described, in the areas I outlined?”
Realtors work on today’s sales not future sales. Unless you have a definite ‘buy date’ or already work / live in the area, most realtors will not spend much time with you.
The best way to learn SD housing is do lots of Internet research and then fly out here with maps and notes in hand. Bring a GPS unit, get a rental car, and drive around.