Thinking about a trip across country

We've done similar trips over the last 25 years with our kids, most times with 5 or more kids. I'd get an air mattress similar to this or narrower. https://tinyurl.com/ybtnmosa On our trips we usually start the first day with an 11 to 12 hour day and spend the night at WalMart or someplace similar then 5-6 hours the next day and 5-7 hrs days after that. Out of camp by 8 to 9 am and then camping again at 2-3 in the afternoon. Many places on the way out and back you may want to spend a couple nights or more as well.This gives the kids plenty of time unwind. I'd plan on 4-5 nights at Yellowstone if you want to see all of it. We stayed 4 nights 2 years ago and could have used more. We hit Independence Rock, Castle Rock and Jackson Hole on the way out and Devil's Tower, MT Rushmore etc, Badlands on the way back. There are many places to hit as well. Just don't try to do too much. Headphones, videos and travel games worked well for us over the years. Headed to Colorado and Utah this summer with 4 of our kids. They're 10, 17, 19 and 21 and still want to go with us. All have been doing this since they were newborns. I do all the driving and it's fine.