Trying to 'help myself', I've tried several searches of the forum and not come up with an answer yet. Doesn't help when the system says I70 is 'too short or too common'.

We have a round-trip from Southeast Missouri to SoCal coming up the end of the September, returning toward the end of October. Don't necessarily want to take Interstate Highway on all legs of the trip when there may be prettier areas to drive. Thinking about a
Northern Route to travel West, roughly parallel to I70 to try to catch some Fall Colors and come back East along I40.
Just to 'introduce' our tow:
Tow Vehicle is a 2017 Ford F150 Super Crew w/2.7L EcoBoost, 6-Speed, with the Teeny Weeny 23 Gallon Bladder. Manual specs list Max Tow Weight as 8500 Lb - refuel every 200 miles or so!
Travel Trailer is a 2020 Keystone Passport 197RB. GVWR 5600 Lb.
WESTBOUND (Northern Route)
Looking at 70 out of St. Louis, MO toward the area of Monument, KS; US40 down to US50: Pueblo->Monarch Pass->Monticello->Flagstaff and west. It looks like I could catch 50 Out of Kansas City or hop down from Topeka . . .
I know this gives several passes and grades to travel on and we can work with that.I'm open to alternate suggestions/modifications. Not on a hard time line, but would like to do it in five-max six days; Six-Seven hour days . . .
EASTBOUND (Southern Route)
So basically I40 to North of Little Rock and US 64 from there. We drove chunks of Old 60 last year.
In years past, we've done a lot of Interstate across the country and we would like to 'stop and smell the roses' a little bit. I appreciate any ideas for either route.
Thanks for looking!
John