A lot of the manufacturers advertise their "wide" boards for sizes 11 and up. "wide" usually means 25.8 or 26.0 waist width at least. But, they also seem to think that you can ride size 10.5 boots on any board, and it's a small difference between 10.5 and 11.5!
If you have your stance set up with big angles, I bet it'd work. If you don't, I dunno. What are you riding now? Can you can test ride one, or at least rent a board with the same width?
edit: idleline beat me to the punch, and he actually rides the same boots and board, so listen to him!