That is the height listed by Jayco for our 2014 31FK, also. Being a bit cautious, I pulled my old surveying elevation rod out of the closet and verified it. In my case, Jayco was correct.
I was in the hardware store recently and passed by the mailbox aisle. Picked up the address numbers to make up "11-6" and stuck them at the top of the driver's side windshield. Now we won't have to try and remember the height as we encounter low clearance signs.
2014 Greyhawk 31FK
2007 Honda Shadow Sabre 1100cc