I found a small number of guest ranches, dude ranches and assorted resorts along the way, and you probably won't be surprised to see that most of them are in Montana. This is just a list showing who they are and what town they're in. The links will bring up a Google Map displaying their location and contact information, and give you a brief description of what the place has to offer.
As you go down the list, the ranches are ordered from east to west, which might help you guess where in Montana some of those ranches are.
Cedar Shore Resort Oacoma, SD
Badlands Trail Rides and Eastview Campground Killdeer, ND
Montana River Ranch Bainville, MT
Hawley Mountain Guest Ranch McLeod, MT
Lone Mountain Ranch Big Sky, MT
Madison Valley Ranch Ennis, MT
Five Rivers Lodge Dillon, MT
The Alta Ranch Darby, MT
Lolo Hot Springs Lolo, MT
Mt Adams Lodge at the The Flying L Ranch Glenwood, Klickitat, WA
Eagles Nest Resort Ilwaco, WA