Going to Glacier without a car

My first visit to Portland was via the Amtrak Empire Builder, which passses through Glacier National Park at sunset. It is absolutely one of the most beautiful places in America, and ever since then I've wanted to go back. So . . . at the end of this month we'll be boarding the Empire Builder eastbound and getting off at West Glacier, the westside entrance to the park. From there we'll take the park shuttle to the campground. We'll be staying for four nights and haven't decided yet whether to reserve at one of the two campgrounds that take reservations or just decide when we get there. The park has an amazing website, with ranger blogs and calendars showing what time the different campgrounds have been filling up each day. We would have waited until September when the crowds die down, but after Labor Day they start shutting down park services, including the shuttle. Traveling the Going-to-the-Sun road is supposed to be one of life's great experiences, and I like that we'll be doing our part to reduce our carbon footprint (is that a cliche yet?) by not driving our own car through the park. According to Amtrak the trains have been running pretty much on time, not more than 30 minutes to an hour late (which is a pittance in train travel), so we should be leaving Portland early Saturday evening and arriving West Glacier bright and early Sunday morning. We'll be using backpacks but since we won't have to hoof it with all our gear we can carry an extra bag or two with food. I got Isabel an awesome Osprey kid's backack from REI, which of course she doesn't appreciate even though in many ways it's nicer than mine. I'll keep you updated on the plans, and of course there will be pictures and commentary on what it's like to make the trip carlessly (but not too carelessly!).