I would add:

- (spare) sunglasses
- something that will protect your head against sun rays - baseball cap, bandanna, ...
- something for handwashing - antibacterial wipes or hand sanitizing liquid/gel
- (binoculars)
- cutlery (fork, spoon)
- small fire extinguisher
- photo of your car from different angles with readable license plate - if someone steals it (which I donīt wish you at all), you will be able to show police how it looks like instead of just describing it

Sorry if I repeated anything already mentioned.