Californians often don't state distance in hours. 8 hours can be 60 miles around here. You are at 544 miles according to one web site. From So Cal, that would be the equivalent of a trip to Lake Tahoe or Grand Canyon. That's very easy to do in one day in a car but for a new motorhome RVer, I'd limit it to 300 miles a day.
My strategy: Leave after traffic the night before and go as far as you can. Then overnight and finish the rest. You can preplan a bit more by figuring how many miles you can get from say 7pm to 10pm or 11pm then find the overnight spots around there.
The other thing I'd say - keep the speed reasonable. You have so many more options at 60 or 63 than you do at 70 when evasive action is necessary.
In the end, all we can do is make sure we have everything maintained and checked off the list, then sit back and enjoy the ride.
BTW, do you have roadside assistance for RVs?