I used to auto-x all the time. Most of the time I’d just use trash bags and throw all 4 wheels in the back seat…and still have enough room to cruise home comfortably (and I’m 6’4.) That said, you can fit 2 in the trunk also.
I also have a rear JDM rear seat with the pass through in my car now. I’ve used it a few times while transporting certain things (exhaust, side skirts, etc).
Also, if you can get your hands on an STi limited, it does come with the pass through though you lose the alcantra like material and have leather seating amongst other things.