The usual location for a rear bulkhead is right at the back of the cockpit. This makes it easier to empty the kayak by raising the bow. (As in a T rescue.) I belive the rear of the cockpit in the Guillemot is between forms 10 & 11. The exact location should be determined by the cockpit cutout.

The font bulkhead location can vary somewhat. In the interest of maximizing the size of the watertight compartment and minimizing the floodable volume of the cockpit, I put it immediately in front of the footbrace tracks. If you thought you might store some gear in front of your feet you might want to move the bulkhead forward some. There is no hard and fast rule because paddler leg length plans an important part in this decision.