I did a CA to Maine and back run last year, and I see some overlaps on some of the sections that I ran or have been on before. If your buddy is really intent on seeing Craters of the Moon, so be it, but IMO, the ride from Elko to Idaho Falls is about as boring as Amish porn. Fuel up at any opportunity you get. It's a pretty good (and dull) hike from the INL lab to Idaho Falls, and there are no fuel stops along the way.
The run from Yellowstone to Cody will be spectacular. If you happen across a gal named Amber in the Yellowstone area who begs for a ride, run! As fast as you can! (I'll fill you in on that story when we run across each other in Le Claire). You'll have a ball on this trip. Be sure to keep us updated.
What if the Hokey-Pokey really is what it's all about?