Really nice list, you have all of the basics PLUS more. So most likely you don't need to add anything, especially with it being your first time. Definitely NO GoPro or Solo, as it will take your focus off of driving IMO; add it later.
You may want to add:
- folding chair to sit on
- food, drinks, and snacks to keep energy up
- notebook with track map to take notes
- lots of layers for weather conditions
And I usually also bring:
- chalk for tires
- rubber mallet
- wheel ramps so I don't have to use the parking break!!!
- bicycle & bike rack because it gets tiring walking everywhere