I live and work about an hour east of there.
There is lots of elk with a good mix of farm and bush. He will also have access to the shores of Williston lake and the rivers off of it. Some good elk hunting country. If I was to go, I would hunt the early season. I have killed most of my bulls in the first 10 days of Sept. Keep in mind that cow elk open up September 15 and go to October 15. Once the cow season starts, the bush becomes very busy! And that will include the lake and rivers. Jet boats, quads, SxS's and trucks will be buzzing the bush. The Go will have areas with limited access, but there is not much in that area that doesn't have some sort of access.
As for outfitter, the area he hunts is pretty good for animal numbers. Ask some questions and get some references, both successful and not, especially not and not just elk, but any hunt. Talk to them, ask them questions about the hunt, camp, animals, guides, food and one of the biggest, communication. That will get you a start.
If you have any questions let me know
Cheers
SS