Nashville is about 3 hours and 45 minutes into day 1, then if you drive 7 hours total you're going to be somewhere in Illinois like Mount Vernon (Illinois) or if you can stretch it to 8 hours, you could make St. Louis: https://citiesbetween.com/buford-ga-and-vail-co Mount Vernon might actually be a decent stop in a smaller town rather than dealing with St. Louis. There are a bunch of hotels along I-57 that you could look into.
Maria