You have to admit that the rear seats in the GP look perfectly executed. Honestly, I've never found much use for the rear seats and mine remain almost permanently lowered w/ a spare tire fastened to the floor, but if I had kids, it would probably be different.
I agree with your thoughts on the rear seat. It was a professionally done job right down to the seat belt brackets and seeing how the car could be returned back with all the original parts was the cherry on top.
another one. Highest mile GP I have seen on BAT, but should still bring some good money https://bringatrailer.com/listing/2006-mini-gp-48/