Here's a suggestion, or a monkey wrench depending on point of veiw.
Any chance of reverseing the directions and heading north from Yellowstone to Darby ,Mt. for West Fest? It seems that you have enough time to make it if you choose. And Mt. is great.
RR's Catnip Hill to Peoria ___Loopin' Seattle to WestFest
It started with some beers __1500 miles to the Dentist
Skeedaddle to Seattle______ A 30 year old on a Three Flags Run