For context, planning on taking the train into East Glacier from Seattle, starting off at the Glacier Lodge and making my way eventually to the West. I am having a very hard time seeing how this will work though, as it hasn't been clear what shuttle options will exist, or where they actually go.
If I can't get from the lodge to say, Two Medicine Lake by shuttle, I would consider getting off in Whitefish, taking an Uber to the airport and renting a car from there, and shift around my itinerary as needed. Just would prefer to keep costs down by not needing to rent a car for the 6 days I am planning to go.