I did a similar trip back in 1989 in my Vanagon camper - generally heading north and east until I got to Chicago, then back to California on what was left of Route 66 with as little freeway driving as possible. Some days I would go 300 miles, others I did less than 100. Took lots of pictures (this was before the digital camera era) and used the American Roadside Attractions book as a suggestion for things to see along the way. It took about a month to do the loop and it was a great trip!
I recently bought a Promaster 1500 (136,) have not fitted it out yet as it is also a toy hauler and there might not be enough room for my vintage microcar and sleeping space.
Have a good trip!

You need a correction to the instructions: Soak the beans in water for at least 6 hours.
Heat a medium-large cast-iron skillet or Dutch oven over low heat. Add the onions and oil. (the rest is OK.)