Buy a trucker's road atlas, it has all the routes that are safe for semi's highlighted in yellow/orange. It the route is safe for an 80,000# 70' long semi, it's safe for any MH and towed.
DO NOT, under any circumstances attempt to drive to the coast using ANY highway North of Williams, CA. to the Oregon border.
I once drove from Redding to Crescent City with a dually towing a 40' 5er, that blunder took almost 8 hours to drive, I think 30mph was the top speed I attained, some curves required both lanes to negotiate.
2000 Winnebago Ultimate Freedom USQ40JD,
ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy