Would it be safe to pull a 35ft 5th wheel on UT-12?

If you are a flat lander, it can be quite intimidating. But it is doable if your truck is up to the task both for pulling up the grades and holding things in check on the down slopes. As mentioned, some sections are quite steep although they were not overly long. The scenery is beautiful but the driver may not have much chance to admire it as it is a demanding drive. We did it this summer but probably would not tow it again.