I live just outside Durango and make the drive to Montrose regularly (most recently just last week). My #1 question to you is how much mountain driving have you done?
On this route you'll encounter steep up and down grades, switchback curves and sheer drop-offs at times with no guard rails. Not trying to scare you but I don't want anyone taking this route in a large rig that's not prepared for it. Even full time semi drivers are caught off guard and end up burning up their brakes and wrecking on this road. It's a great drive in a car but even that can be a puckering drive for some. Many a time I've come around a curve to find a car half into my lane trying to get away from the drop off on their side of the road. Google Million Dollar Highway for pictures and videos.
Alternate routes include going west to Mancos, then north over Lizzard Head Pass before turning back to the east and rejoining Hwy 550 in Ridgway. Still will have some pretty good grades but not the switchbacks & drop offs.
Heck, there's even been times the only safe route was way out west to Cortez, Dove Creek, Slickrock and back east again.
PS. If you're a John Wayne fan the town of Ridgway (and surrounding area) was the setting for True Grit. There's a restaurant there by the same name with lots of memorabilia.
Barry, MSgt, USAF, Ret. & Rose
2017 Ford F150 w/ 3.5 EB
2014 Coachmen Viking 17FQ