This is why I love this site. Thanks for the consult, Lukas!
I keep hoping that someone who's already taken delivery of a 2013 F8 will take off their fork caps and provide the measurement, but so far no one has been forthcoming. I'm tempted to see if the parts folks at the nearest Beemer dealership will ante up with the info.
If no one's come up with the data by the time I pick up my bike, I'll take the caps off and measure them. Since it seems that the Shiver mod is now out of the question (and BMW can't/won't be prevailed upon to fix the problem themselves), the ball needs to be started rolling on coming up with a new solution.
I wasn't born to ride, I was born to work.
But I got laid off.