Just my opinion....
If I get conflicting routes between my on-board Rand McNally, versus Dee's Garmin, versus some source such as Google Maps, I ALWAYS AM GOING TO BELIEVE THE Rand McNally most as its the only one that factors in my weight, my length, and my height. Then, if there are differences across sources with a tendency preference toward the Rand-McNally, then I confirm that preference against my Rand-McNally Deluxe Motor Carriers' Road Atlas which highlights in yellow any road that is approved for use by semi-tractor trailer rigs. If the coach Rand McNally says a route is best, and it is confirmed by the Motor Carrier's Motor Carrier's Atlas, then that always is the way we travel....
That process has never failed me for a rig this size (I ignore the fact that I am towing the Honda in overall length and weight issues in my coach specs).
I give no credence to my Google results or my "auto-assuming" Garmin GPS routes. They are irrelevant to my routing IMO !!
Gary and Dee, Zowie and Bowie (traveling cat sibs)
2019 Cornerstone 45B, X15-605hp, Imperial, Spartan K3,
2013 Honda CR-V toad, Demco Excali-Bar II,
Demco Baseplate, Demco Toad Light system, 73 de W5FI