We're headed to the same destination leaving Saturday as well, going through West Yellowstone along the way- arriving in Glacier on the 1st. We're planning on taking advantage of dispersed camping around Hungry Horse Reservoir in the Flathead national forest. Currently there are no fire restrictions or fees, but bears are always a concern. There's dispersed camping on both sides of the reservoir and you can download the Avenza maps app and search for the Flathead NF MVUM Hungry Horse Ranger District map.
We love Avenza, open it while you still have cell signal and it will track you on the map even after you're off grid- just don't close the app, and all the forest service maps are free!
Have a great time and stay safe!
-Heathen