It's a piece of cake - charge in Gila Bend - skip Yuma - charge in El Centro - when I go to Carlsbad I usually leave El Centro with 220 rated miles
Exactly how I drive from Mesa AZ to Oceanside. On the return I take the scenic two lane to the SC in Indio then Quartzite and home. I charge higher and longer at Quartzite so I can skip Buckeye.
i have made this round trip more than 30 times and have charged at every SC on 1-10 and I-8 as I tried different ways to do it and as new SC's opened up. El Centro was critical to making it easy and the San Diego SC is a great safe zone.
I depart with a full range charge, charge for ten minutes in Gila Bend so I can skip Yuma, then at El Centro I do a long charge so I can skip the San Diego SC and make it nonstop to my house in Oceanside.
For me the return works better on I-10, I leave Oceanside and because it's shorter and more scenic take the two lane direct to Palm Springs and the Indio SC then just grind it out to Quartzite and arrive home with a few miles left. You can run all the way from Indio to Phoenix and never touch the steering wheel. AP works absolutely great on that long run.
My road trip strategy is to depart full, drive as absolutely far and as low as I can. Do all chargeing on the bottom half the battery as much as possible. Only charge enroute high enough to make the next stop with a 10 to 15 % buffer, arrive at my destination as low as possible with a little buffer left. Doing that I can make the run almost as fast as driving an ICE.
After a few legs you will get comfortable not to ICE think and sit around filling up on the slow charge upper half the battery. Unless you are enjoying a great meal there is no reason to sit on the charger, on the slow side of charging, adding range you don't need. Unneeded range is just completly wasted time sitting at an SC. Until you get comfortable with it go ahead and over charge.
The range assurance is a complete waste of time. Just set your destination to the next planned charge stop. Open the energy app and select trips. Then charge to 10 to 15 percent extra. Before you believe any displayed number that looks wrong, cancel the route and re-enter it. Not uncommon for the energy use data to get messed up and say you need a charge when you don't. So cancel and restart before you panic and go back for more charge,
I make the the run in a P85D on staggered 21's at an average speed 5 to 9 over posted. That's about the worst Tesla range possible and I make all the legs with no problem.