I found a thread where someone unbolted the seat rails and mounted the four legs to aftermarket seat mounts in his 1M (link below). He lost the fore-aft adjustment but by my measurements it looks like you could gain about 2”!
I’ll see if I can find the thread. I need to take some more measurements but it looks like the front/rear bolt distance is the same as any aftermarket bucket seat (~11.25”) and the width would work with a set of the Brey Krause mounts. If you’re the only one driving your car it could work. I might give it a shot. Worst case I have a set of mounts for an aftermarket seat.
https://www.1addicts.com/forums/showthread.php?t=698747