I hunted antelope around there 3 years ago. I made the drive out there without an exact place to go. I stayed in Glendive, but I hunted in between Jordan and Miles City down along Hwy 59.
My aproach was asking landowners personally. I talked to 7-8 landowners along the way, told them I had a tag and was interested in hunting antelope and everyone but 1 said no problem. And the 1 wasn't rude, just didn't allow anyone but family. The rest were some of the nicest people I had ever met. Some went so far as to show me their actual land boundries on a personal map, as they usually own a few sq. miles.
Usually the only request the had was don't hunt anywhere near their cattle, if they had any. I ended up taking a nice goat on some ladies property, and she would not take anything from me. The only thing I could get her to take was a couple jars of canned salmon.
Only a suggestion, might not work for everyone.