I have shot Pdogs south of the mp170 exit on I-90. There is a KOA right there and an 1890's frontier Town tourist feature.
From there cross south of I-90, turn back east and then turn south on Cedar Butte Rd. Once down into the river bottom of White River either go right and up a ways to a hardscrabble looking farmstead and ask around there. Or you can keep going south and take pot shots from the fence line at em.
You will need a SD varmint permit, I think it was $20.
I have shot in this area two different time in June and they were thick in a lot of places. Used my 6mm, .222 and 22-250 on shots out past 600 yards.
Best shooting I had was in this area. Dogs left, right and center as far out as you wanted to shoot.