Try looking at the Row by Row 2018 website. They have posted all the quilt shops participating in that event by State. Perhaps your route into Yellowstone will be through some of those other cities as well. Bozeman has a couple shops listed, one in West Yellowstone, too --
http://www.send-it-home.com/ Those are the only ones I saw close to the Yellowstone border on the row x row website:
https://rowbyrowexperience.com/store-finder/