Let me not answer your question by sharing that I did a road trip in a 2012 Prius from chicago across the country to SoCal via Washington DC- Savannah GA - Arkansas - Las Vegas and arrived home in CA. It was in the winter months and I stayed in Walmart parking lots. I had purchased suction cup mounted shades for all windows and left the car on with the heat set to as low as possible sleeping in a winter sleeping bag. I’m 6’3” and purchased a nice hard side cooler that lived in the back seat floor with the front passenger seat moved forward. When it was time to sleep I folded the rear seats down and took the cooler I used for food and placed it in the foot well, added a few deck chair cushions to bring the level up and slept comfortably. I’d climb in the back door and laid down, reach up front and lock the doors. Heat would be low slowly draining the battery, engine would kick on now and again to charge the battery and then turn off. It was tricky finding showers but truck stops and local gyms worked out well. Best of luck!
I don’t own an EV6 yet but these might work? Looks like $250 for a full set
Windshield Sun Shades, Car Window Shades and Car Window Covers by HeatShield: The Original Windshield Sun Shade