Focus on areas that have huntable terrain if your doing spot and stalk
Hunted this same area a lot when I lived in SD, had best luck spot and stalking goats around there. They see a lot of single buck decoys which makes it tougher to decoy them in.I was born and raised in SD. We did most of our speed goat hunting in the nw corner from Belle Fouche to Buffalo to Camp Crook. A lot of public land in that area. Some of the tactics we used included, blinds on water holes and open gates in pastures, half dozen silhouette decoys around a blind in a low green spot on an alfalfa field on a dry year. Single buck decoy during the rut. Spot and stalk. Many different ways to skin that cat depending on the field conditions you are dealing with.