Get yourself a racing helmet, then it'll be just about perfect.
I, too, had this very same problem, until once at the track in my '97 Cobra. It was the first thing I'd taken to the track with even the remote possibility of 13's, so I took along a motorcycle helmet that was approved. The first thing I noted was that with the extra skull on, I could rest my head against the headrest and actually see out of the windshield, as opposed to looking at the roof of the car.
The other thing that is a major problem with my use of the headrest is that I'm 6'1" tall. To sit in a car the size of a Mustang, especially my Cobra, requires the seat to be all the way back and the seatback to be leaned way back as well, just to provide proper arm reach of the wheel. I would be more comfortable sitting closer to upright and having the seat a little farther back, but I'm at the end of the travel. This leans the headrest even farther behind me.
JS