Has been a few years since I took an RV across Ca 36, Out of red Bluff its two mile straights with 90 degree turns, is a twisty pass and I remember tell the wife, these turns are so sharp I swear I can see my tail lights around the turn in front of me LOL
But on the pro side there are a few great vistas. Did it once and that was enough, if you go this route take your time and fuel up before.
There are a lot of state and private parks on 299, part is very scenic and parts of the forest mountains are clear cut, and what saving the redwoods is all about. Also a side trip to the trinity's is fantastic, IMHPO 299 is better, whiskey town lake is a great spot to stop and fix lunch.
Enjoy your trip