I'll speak for CA. There is a state park at Morro Bay that would make a good base camp. Other private parks in the area. I haven't stayed there so I can't vouch for TT length restrictions. I'm referencing it off of location. That would put you on the Pacific Coast Hwy but not worrying about towing on it. You could head north towards Monterey which is a beautiful drive. Hearst Castle. Big Sur. More stops than you have time to make. Monterey is a good place to spend a day but if you want to do that, I'd stay in that area.
South from Morro Bay, you have San Luis Obispo and Pismo Beach within 50 miles.
Yosemite is a must although that's not a great time of the year to visit. The crowds will be large and the waterfalls likely dry - but I'd still go if it was my only chance. You can drive the valley in one day. It's not optimal but it's better than skipping in my book. If you have three days, you can take the short hikes and go up to Glacier Point. If nothing else, consider it a scouting trip for future adventures.
Sequoias: You have three options. Mariposa Grove is inside Yosemite. Not as big at the other two options but would save time and still magnificent. Sequoia NP and Kings Canyon NP are sister parks that are adjacent. General Sherman, the largest tree, is in the Giant Forest in Sequoia. General Grant Tree, the second largest, is in Grant's Grove at Kings Canyon. Kings Canyon is two parts: Grants Grove which is a sequoia grove at 5,000' (if I remember correctly) and Cedar Grove which is the valley. Cedar Grove is beautiful but is a long slow drive best reserved for when that is a primary destination. I like Kings Canyon over Sequoia because it is a much easier drive and slightly less crowded. It's also an easier drive from Kings Canyon to Yosemite.
If you spend a half day in San Fransciso you can ride a cable car, eat clam chowder in a sourdough bowl, and see the Golden Gate Bridge. Yes, there is much more but this will check some big boxes and save time for nature that folks in RVs tend to prefer.
Head up to Red Woods and OR Coast from there. I always wanted to visit Napa Valley but haven't gotten to it so I can't speak first hand.