Obviously you will be taking I 10 to the coast. We stayed at Tapo Canyon Campground when we did the LA area. It is quiet, a bit out of the way but there is easy access to the freeways to get to the LA need to see sites. Then head over to Venture and take highway 101 up the coast all the way to San Francisco. You will be okay on the road running a 43 footer, but finding any RV Parks from Morro Bay to Monterey will be tough. There aren't many to start with and then add to the mix your length makes it pretty much impossible. San Simeon State Park has a max length of 35. Riverside max 25. I could not determine a max for Pfeiffer Big Sur State Park (call to book and conform max length). From Morro Bay to Monterey is only about 150 miles but it is a s l o w drive and because of your size, there won't be many pull outs that you will fit. What I would do is drive your rig from Morro Bay to Monterey and then back track with your towed. Honestly, the drive from north to south is more spectacular IMO. If you do stay near Monterey make sure you take in the Aquarium. Plenty of RV Parks in Morro Bay that will accommodate you. Lots of RV Parks near Monterey starting at Carmel by the Sea but book as far in advance as you can because this area gets busy. We have no recommendations for the San Fran area. We always stay with friends sorry. But San Fran is only an hours drive from Napa and if you like wine this is a must. Napa Valley Expo is our go to. Concrete pads, well manicured and close to the wine!

We have not stayed anywhere in the Sacramento area so you are on your own after Napa.
Good luck and safe travels.