I stomped in as tight as I could and strapped down and then pulled my foot out of my unlaced boot. There is a gap right at the heel, but the highback angle just won't let it go back any further. The boot is right against the highback a couple inches above the heel.
Looks like to me it is about 1/4" off-set to the toe side. 1/8" further back would be center. The only way I can see to even this out any more would be to decrease the highback angle so I can push back a bit more. I may try taking it down to 10 degrees rather than 15.