I don’t know about marten, but a friend 45 miles west of me showed me a trail cam pic of a fisher two or three years ago. Picture was very clearly a fisher and in the daylight. Very surprising to see, so who knows what all wanders in from time to time.
I had heard they relocated some there in recent years. A couple of years ago I drove south of Spearfish to see what the habitat looked like. I did see some areas that looked like potential marten habitat, but it sure didn't look like much of the area was good habitat; it looked too dry to me. Mostly north facing slopes and some darker (damper) canyons that looked okay.