We took the ND thru MT section. Or some of ND anyway. It's a lonely road with few campgrounds, cell phone service only in the widely separated towns. The towns all have service stations and some sort of market.
I believe you'll have to depart Rt 2 and go south for boondocking. There are a long series of parks and recreation areas along the Missouri River. At the east end it is close to Rt 2 but goes south west from there. Ft Peck is one.
We actually plan to reverse the route from Bonner's Ferry ID thru to Michigan this summer.