I travel that section at least once a year (from Phx AZ to Roseburg Or and back) pulling my 40' 5th wheel.
The I-5 travels from Redding North and into Oregon are not to rough.
But the routs south of Redding down thru the rest of Calif are terrible. Pulling a trailer, you have to stay in right lane, and stay at 55MPH, along with all the Semi traffic. Those lanes have been warn so badly, and un-maintained, the trailer just gets pounded for hundreds of miles.
I have refused to use that route for so many years now. Besides, it is baron and not very nice scenery.
I now cut off the I-5 around Shasta and and head East to the 395 along the Calif/Nevada border. Much less traffic, roads are nice, and the scenery is soooo much nicer and Lush. At least until you get down around Mojave (scenery wise).
Just my .02
Gery