Moki Dugway is fine as long as you are in a toad or tv ONLY.
Oh My God Road north of Idaho Springs, CO lives up to it's name. Did it once coming down in a Suburban and met a road grader coming up. Won't go into details! :-)
Then there was a forest road north from Dolores, CO someplace what was about 3 miles of single lane shelf road. But it was wooded so you would not fall far. God only knows what one would do if you met someone coming the other way!
The winner for us, though, was up west of Banff someplace. We had done some exploring up in the hills and were supposed to take the Such&Such Road back to Such&Such (obviously, don't remember the name of the town). So we start on it. Hmmm, divides into North S&S Road, Middle S&S Road and South S&S Road. OK, swell. We chose one of them; no good reason, just a WAG. Well, we made the first hairpin turn and knew this was an issue. Had a dooley truck at the time. It had rained the night before. It was single lane shelf with no downside protection and about 400 feet straight down to start. We head down. Right outside wheel of the dooley was over the side at times. And places where there was some washout from the rain. Other places with running water across. Four plus miles! I did not worry about meeting anyone as no one would be crazy enuf to drive this! We got to the bottom and there was a nice stream and place to pull off a little. We got out and hugged each other and had a little conversation with God about thanking Him for taking care of us.
When we got back to the RV park and talked to the owner - who had been there for some time - his eyes got wide as saucers when we told him where we drove down. He had never met anyone - tourist or local - who had ever driven down that in anything but an ATV.
But I am here typing ..................
Be safe!
And Merry Christmas!