Rode the route you are planning on my motorcycle and would not consider taking my coach thru it. The main reason is the abuse it would take. It is a winding twisting 10,000' mountain pass which has many steep twisting slow hairpins. Things would tend to be well re-arranged inside the coach even if well packed and anchored. The other reason is the abuse one would heap on the brakes, even with a good exhaust brake the descent would definately take a toll as coaches do not have the gearing that a commercial tractor has to hold back on a jake or exhaust brake alone. It would be do-able, but not enjoyable. Park and do the trip in a car or motorcycle, it is amazing and well worth the trip. Do it in late summer and expect large snow banks on the roadsides.