The grade north of susanville is steep but there are plenty of turn outs. Once you get to the top, 139 is a standard 2 lane road. I have been on the road dozens of times as we have an escape house up that way. While I have not driven it in my MH, I was with a buddy who drove his 40' Dynasty up the road pulling a large trailer with his Corvette in it. We just took our time.