Glacier National Park from MN, possibly Pacific coast

We decided last night to focus on Glacier. We are tentatively planning 1st night Medora, 2nd night Great Falls, nights 3-6 east side of Glacier, nights 7-10 west side of Glacier, 11th night Billings, 12th night Bismarck and home next day.

Any recommendations for campgrounds in/around those cities/areas? Looked at the KOAs but at $70+ per night gets expensive. We enjoy state parks but do want electric hookup and ability to dump tanks on way out.

Thanks to all who've chimed in so far.