If you have the time go through South Dakota and spend a few days in The Black Hills. Mt. Rushmore is the tip of the iceberg. There is so much to see and do, people buy summer homes there. Then go by Devil's Tower and on to Badlands
N P. Then you can stop at Wall Drugs for some kitsch and spend a day at Custer Battlefield N M. Last year we went from there to Yellowstone and Grand Teton N P's (highly recommended but maybe too much to include with Glacier) but you would presumably continue NW to Glacier. I personally wouldn't rush The Black Hills and so would probably save it for another trip if I couldn't give it at least a week. The others (obviously not Yellowstone and Grand Teton) can be done a day or less each if you press it although that's not ideal. Bottom line I think is if you have two weeks, skip Black hills for another time and do the rest but if you are not rushed this could be an awesome 6 week trip.
2015 Crossroads Cruiser Aire CAF27RL, 2018 F250 diesel crewcab SRW 4WD short bed, Trailer Saver hitch with Reese adapter on Ford OEM underbed 5th wheel connector.