We did that trip as far as Williston ND last summer. Stayed in Iron Mountain MI and Superior WI, then Bemidji MN, Grahams Island SP in Devils Lake ND and Lewis and Clark SP east of Williston ND. We wanted to get to Glacier but the fires this summer turned us south from there.
Skip Superior and head across to Two Harbors Minnesota. Burlington Bay Campground - great view of the lake.
Two Harbors
Be sure to stop in Bemidji MN and see the Paul Bunyon and Babe statues.
About 1/2 hour away is Itasca SP and the headwaters of the Mississippi.
Lewis and Clark SP was the highlight of the trip. Full hookup pull through sites with great WiFi overlooking the Missouri River for $22 a night.
Williston is an oil town. If you need some supplies this is the place.
US 2 is a good road. The worse section is in Michigan. The rest is mostly smooth 2 lane road and 70 MPH speeds. ND is mostly boring.
Somewhere along the road in ND was the Geographical Center of the US. We didn't stop but were curious as to why it was so far north. I'll leave it to you to find the answer.