"Easiest" route to Clearlake, need some advice

I need some advice from my NCKA brothers & sisters...

On Tuesday I have a job in Lakeport (geophysical testing for a new school), and I need to get my enormously heavy trailer to Lakeport from Menlo Park...

I do not care how long it will take, I just want to take whatever route has the easiest grade.  I know the road from Calistoga to Middletown is the worst...

How bad is the road/grade from Hopland to Lakeport (Hwy 175) versus the road from Williams (Hwy 20) coming in from the east side?

I'm towing a 15,000 pound trailer with a 2006 Dodge dually with 4.11 gears and turbo diesel Cummins engine... plent of power (and brakes), I just prefer to take it easy on my own equipment since this is my livelihood.

Thanks for any routefinding advice...

Backcountry

How bad is the road/grade from Hopland to Lakeport (Hwy 175) versus the road from Williams (Hwy 20) coming in from the east side?

Steeper,twister and really narrow I would take 101 to Ukiah and hit 20.

I hadn't even thought of that, but I just looked at the topography on Google earth and it sure looks like the safest bet... thanks a bunch for the advice!