Don't believe the doom and gloom sayers! The trip is somewhat remote in places but not a problem if you SLOW DOWN and enjoy the trip. I did put some 3m type film on the lower front of the 5er, not sure if it prevented any gravel chips or not. Again, just match speed to conditions, it's not a race.
We drove up and back in 2016 and cracked our windshield in Montana.
I carried an extra 5 gal gas can; a spare tire for the 5er and pickup; and an extra unmounted tire for the 5er and pickup. Never used any of it but it was comforting to know I had the backup.
ENJOY!