I can't give exact locations but you are pretty much surrounded by them, if they made it through the last plague.
If you are located in Gillette, why not use information from the locals.
In the past I know guys that got good information from some of the sporting goods retailers in the area. Find out where the ranchers are getting their supplies and check with them.
I find a good restaurant with ranch pickups parked outside, and get a cup of coffee and go ask the guys with the hats if they are ranchers and if they know of any pds around. I just walk right up to their table and start talking.
It shouldn't take you long in that area to find them.