I would never be able to sleep if I recommended that anyone should take a large MH over Hwy 108 in either direction and they did it on my recommendation. Just to narrow and too steep and you are bound to have a problem somewhere along that route, either going across the center line, loosing power, or loosing brakes down a 26% grade even if you are in first gear.
I recommend it in a car or pickup truck or a motorcycle. But to each his own. And yes cal trans shows this route as a RED route and MH's over 40 ft are prohibited on RED routes. See the link in above post for map.
here is a link, when the map comes up, click on number 10 on the map and find Hwy 108
Cal Trans MapSo please use common sense if you decide to take this road in your MH