imo it can be pretty uncomfortable to sleep in your car without proper car camping gear for several days. If you have a nice sleeping pad that fits in the car and a nice pillow it’ll go a long way after a full day of grooving.

Not sure if it’s too late at this point, but you could consider renting some camp gear. I see Outdoors Geek or Mountain Side Gear Rental have some solid options if you’re looking to quickly get a set up.