MMC themselves are usually very reluctant to make any changes to seating, or pedal arrangements, because of homologation issues. However, they do have another company -
Aero Racing - who will be fitting the Track Day packs on the 4/4 Sport, who I am sure can be used to make changes to the seating arrangements; though I am sure that will be as aftermarket suppliers without the same comeback under product liability (e.g. the spinners in the track day pack are certainly not homologated!).
Aero Racing certainly have the ability to build a seat with much less dense foam, and may be able to make other mechanical changes to make you more comfortable, or even get you to fit in properly.
If this route does not work, then if may be also worth talking to Steve
Simmonds and Shaun at
Allon White who I am sure will come up between them with a remedy to your issue. HTH.
