Since Williston was my home town, very familiar with the area.
I'd agree with Glasgow, MT being open on the west side of things. Your eastern end of congestion should be Minot ND. It's packed solid too.
There is a small campground attached and behind the Cenex station along US 2 at Berthhold ND. It's west of Minot but I have observed openings there while motoring past there.
Rugby ND has a little bit of campgrounds right where ND #3 and US 2 intersection occurs.
Devils Lake has some state parks nearby, that is if the ever rising Devils Lake has not flooded them out.
Grand Forks has a KOA just south of town along I-29. There is also a very nice state park some, oh, about 22 miles west of Grand Forks right on US 2. Turtle River State Park.
US 2 is four lane all the way from the Montana border to way out into Minnesota. Good road.
The Cenex stations previously mentioned are a regional brand but are known for having quality fuels. Rugby, Devils Lake are both right alongside the highway, in addition to the Berthhold site already mentioned above.
