Hello there. I usually hang out in the Truck Camper section of the forums because that is what we own. However, we've been thinking about upgrading. I've looked at a few manufacturers and seen 11'3...
My Winnebago is 11 feet 3 inches to the top of the air conditioner, the highest point on the MH. That is, as long as the TV antenna is down. >G< I use a 12 foot rule. I won't drive UNDER anything that isn't at least 12 feet tall.
I would bet that wherever you got the 11'3", it was to the tallest point.