The 8-way power driver's seat is easily tilted back a bit to get as low as it can. This may bring your leg room down even more, but give you the extra head room you need for the helmet.

Basically the horizontal adjustment switch, push down the back part and front part until they bottom out. Then bring up the front until the seat tilts back just a little bit.

Now you should be able to lean the back of the seat rearward a bit (may require sliding the whole seat forward slightly.

Not sure if that helps or not.

Good luck!