I live in Des Moines. Welcome to our city. Grab a Zombie Burger before you leave town (go to the mall location if you have the RV already) then grab some Hurts Donuts for the road trip!
I'm part of the group of people that has two active school-age kids and we have full-time jobs so when we get a chance to go in the RV we go and don't have time to smell the roses as some suggest here. We'll run across Country using the entire day's daylight hours even if that's 12 or 13 hours in a day.
One tip I have to help you decide if this is feasible for you is to plan your route using Google Maps but add 20 minutes to Google's ETA for every 3 hours of drive time to account for gas stops and the slower acceleration than a car. There's no reason why you can't run at freeway speeds but if the wind picks up much above 15 mph then you're going to be significantly slowed down.
Also run your route through www.flattessroute.com and look for any elevation changes of more than about 1000 feet in a short distance. Add 15 minutes to your ETA to account for every very slow climb and descent.
Even though you could spend a week in every place you list you can, if you choose, spend a day. If seeing the #1 thing in each park for 2 hours then moving on is your idea of a vacation then go for it. Not our place to disagree with your idea of a vacation.