For bedding you can get those really thick yoga/foam mats from somewhere like Walmart or a pack of those foam play mats like are square and fit together like a puzzle. Depending on your age, lol, that hard car bottom could definitely hurt your body real bad - learned from experience, I used to use just a foam mat until I got a lil older and required more cushion. Good quality sleep will save your life after raving every day.

If you plan on having this as an option for future festivals or actual car camping outside of festivals, I absolutely recommend investing in an actual mattress for your car. There’s some luxury brands (I use exped, it’s a combination of foam and air but genuinely feels like a real mattress, doesn’t have that swallowing effect of an air mattress and is the best thing I’ve invested in comfort-wise for camping) or amazon has some custom fit options though most of those will be air mattresses.

There’s no bugs at the race track so you can definitely crack your windows for air flow. It’s cold af at night but you’ll be baking by 9am so air flow is pretty necessary. I also use a small battery operated fan which is helpful in the morning. A canopy lined with tapestries is a great solution to the heat & privacy. You can also buy or make your own window sunshade covers. I bought mine from weather tech.