We just drove 191 up from I10 to I40. Very little traffic ---as stated no guard rails very curvey and slow. I am sure it gets close to 10,000ft in elevation. The mine at Morenci is very interesting. At times you think you are on the mine haul road going into the mill.
I have lived in the mountain west all my life so I am very comfortable on mountain roades. I found 191 to be great mountain road. We stayed at a NF campground at Hannagan Meadows it would be to small for your 5er.
If you do use 191 get ready to see lots of burn scare. There have been big fires down there in the past couple of years.