We just booked yesterday for some campgrounds in June, Van Damm SP near Mendocino, then a private one in Klamath, then a SP near the Sand Dunes in Oregon. some State Parks still have availability BUT finding ones that take a 30ft travel trailer is tough. We also booked a private on outside of Portland and are about to book the rest of the trip ASAP, but there is still some availability, depending...
Oh, we went through Vegas last July and I thought we would die from the heat, it was awful!
Half Moon Bay has a nice campground on the beach nearish to San Francisco by the way. And here in Santa Cruz there's quite a few campgrounds and the one in the Redwoods may have spaces still, the beach SP ones prob full.