Just got back from Montana. Didn't do any backpacking but did some long day hikes on trails that backpackers were on. Happy to share info. Some in Bozeman and Missoula areas, also went to Glacier. Turns out that you can get a campsite in the park any time in the summer so far without a reservation. Might be handy for getting there or if you want to stay a few days after your backpacking trip.

Went on Hyalite Lake, Sacagawea Peak, Pine Creek Lake (didn't get to the lake,) Devils Glen, and Blodgett Canyon hikes from Hiking Montana guidebook. Camped at Bowman Lake in Glacier, which is usually available in summer. Sacagawea Peak could be turned in to a backpaking route imo.

Want any info let me know.