That is sure going to be fun Craig!
Off the top of my head you of course have lot's of places for fall colors. Though you would need to decide for it whether you wanted East coast or West coast. I could suggest hitting up Yellowstone the 3rd week in Sept since fall colors isn't a big deal there, then the 4th week in Sept hit the Tetons. From there follow the Fall Colors down in to Colorado spending a week or two there following the progression of the fall colors in the passes off the I-70 west of Denver and then heading over towards Ouray. After that head west and hit the fall colors in the Eastern Sierra the 2nd week of Oct. They fall colors will be fading at that point there, but you should still find some good scenes to shoot. Then swing over so that you can be in Yosemite around the 4th week of Oct into Nov as that's when the fall colors look best.
After that, I would head North up into Oregon and Washington. There are just too many options to list there. I would suggest a bit of a loop, where you go up more off the I-5 and hit places like Crater Lake, Mt Saint Helens, Columbia River Gorge, etc. Then on the way back south take the coast hitting up places like Cannon Beach, Bandon Beach, down into the Northern Calif where you can shoot the Redwoods. That would take you into Dec.
From there head to SoCal and shoot our awesome beaches here, like Laguna Beach, Newport Beach, etc. Head down to San Diego and shoot La Jolla and the awesome beaches there.
From there head back up East and North and go to Joshua Tree, then Trona Pinnacles, you can hit up the Eastern Sierra again before heading East to Death Valley. Then from there head to Valley of Fire north of Las Vegas. You can also see Red Rock Canyon in Las Vegas. Then head to Arizona and shoot all of the awesome places there, again too many to name them all.
You will have a blast, and to Ben's point about the weather, it's totally easy to plan a more northern route in Sept and Oct, and then later in Dec and January have a southern route when heading back East so that you can avoid the worst of the snow. With chains you can navigate through some of the snow storms when you are south enough to say shoot the snow in the Grand Canyon. I don' t think you would want to navigate the snow in the winter time in say Wyoming though.
If your RV doesn't come with a Wifi Hotspot, be sure to hit up Alan. I know he has a very good wifi hotspot set up on his RV so that even when he is traveling in his RV we don't even know it here because he is still able to stay online with us.
And for sure when that time comes, we have a lot of FocalWorld members spread out across the US and it will be awesome to meet up with you and your wife on occasions.