Re: seat questions?
You can find space in just about anything.
I just depends on what your willing to do or give up.
You can stretch the car in the front. (lots of work, or is it?)
You can raise the dash up.(hampers steering angle)
You can widen the area around the knees.(more work again)
Moving the seat back helps but sitting more upright stretches the legs a bit more.(easiest to do)
Push the pedals forward & or redesign the pedals so as to not loose travel when it hits the steering rack stop.(push more with the toe & less with the ball)
Like you mentioned, thinner seat.