You are forgetting that your feet do not sit on the middle of the board where the waist width is the smallest. Your feet will be on the insert points away from the sidecut's center. This means the board is wider at those points. So you might have an inch overhang on the direct center of the board, but it will be less when you measure at the points where your feet will actually lie.
You are also measuring in a way that suggests your feet will be at 0 angles. The more angle you rock, the less overhang you will have.
You have a size 10 boot, don't worry about a wide period. I have a size 10 boot that is high profile, and I can ride boards in the 152-155 range without overhang issues.