You could skip the North Dakota Badlands and head south from Bismarck to I-90 and then west to Exit 131 where the Minuteman Missile National Historic Site visitor center is. Lots of good information on the Cold War plus tour through a missile launch control center and also get to see an actual missile silo with a inert Minuteman missile installed. BTW - all of this is right next to the South Dakota Badlands which are very impressive. Campgrounds are close by the Minuteman site and at the entrance to the Badlands. Link:
https://www.nps.gov/mimi/index.htm
(disclaimer: I was on the first Air Force missile launch crew to accept this particular Minuteman flight from the Boeing Company in July 1963)
Bill