While we were in Monument Valley a couple of weeks ago we decided to check out Moki Dugway. Because it was so close I wanted to see it for myself. Very scenic drive, we drove up from Mexican Hat on ...
The Dugway is wide enough to be comfortable with an RV, however the two times I drove it without the trailer it was washboarded enough that I'm glad I left it behind.
By the way, if you do get to the top of the Dugway, be sure to take the Muley Point Road to the end. Another often washboarded road, but the view at the end is wonderful.