I just made that run from Coburg OR to home, Placerville CA in the rain last month with a 35 ft Hitchhiker I bought in Coburg
No problems , only had to get into 2nd a few times = 40 mph , 99 Dodge diesel injectors, edge ez box , ATS auto
Most of the uphills are two lanes with a wide shoulder that the really slow truckers use , pay close attention to the truckers around you , they change lanes to keep their speed up , If you don't manage yours , or if a truck pulls in front of you and kills your speed you may end up in the shoulder lane stuck going real slow to the top of that grade