So... I'm one of those guys that fit 1 in the trunk and 3 in the back WITHOUT removing the seat cushions. It is a very snug. Here's how it works:
4 square 19x11 wheels wrapped in Nankang AR1 305/30/19 (18's would be easier). I put them in tire totes and place towels on the seats to keep things clean. 2 tires sit side by side parallel behind the passenger seat. The 3rd tire (behind the driver) sits perpendicular nesting into the middle tire. That allows me to still recline my seat and drive comfortably. So, it does all fit but it's a PITA. Plus, I can't take anyone with me UNLESS they are tiny and can fit in the passenger seat far forward. See this video from last year:
That's why I'm leaning towards this hitch setup. Although, I do hate the idea of a hitch on my sports car, I'm starting to tire (pun intended) of putting the tires in the car. Finally, tires after a track day don't smell the best.