We love mountain driving and have taken 550 south from Montrose to Durango many times with our 40' MH. However, some don't like it for steepness and curves. Why don't you drive your toad to Silverton to see how you like it? That's the 'scary' part .... Montrose to Silverton. It two lanes & if you always drive within the lane you'll do just fine. Heading south you will have a steep drop-off on the passenger side so you'll need to stay in your lane.
Many RVers and semi trucks drive it.
The alternate is taking 145 south to Cortez. It's still steep and has curves but a little milder.
From 160 at Durango, head south on 550 for an easy drive to Albuquerque.
Albuquerque to Las Vegas? I-40 west to Kingman, AZ then 93 to Las Vegas.
Las Vegas to Montrose? I-15 north to I-70 east.
Routes just depend on what you want to see inbetween. We rarely do interstates..... love the secondary highways.