Any drawings for the upper deck??
Also an advise , the lower deck looks like a carpet deck , also with the 3mm thickness , it will be very unflexible !!!
I suggest to keep the 3mm but to find some points to dremmel , maybe under the servo or speedo , also something for th emotor maybe??
I like my car with a lot of steering and with unflexible decks but i think that this will be too much !!!