A pal of mine has an original Boxter. Very much a garage queen, weekends only car, when dry as it runs semi slicks and is lowered in KW suspension if I remember rightly...
Anyhoo... I cannot fit in the drivers side at all, but at 6ft4 and 22 stone, it’s never gonna happen. I can just, get into the passenger side, it’s still a crush, knees and shoulders, but I can get in. Ok, I’m a Cadbury’s misshape, but they are not spacious inside.
6ft and under, I think you’ll be fine. 6-6ft 2, you’re pushing it; wide shoulders and or legs/arse, you’ll struggle