I guess turning perpendicular to the wind is kind of what I hoped it would do. It means the boat is balanced. Loading down the bow will help turn it upwind which is great when you want to go upwind, but kind of pain when going downwind.

Typically people like there boats loaded a little heavy in the stern because a kayak is harder to control going down wind. They sacrifice a little ease of handling upwind but consider it worth it. This same handling can be achieved with a skeg which moves the center of effort for the water backwards.

I would not make any modifications to the boat yet. Try putting water bottles into the ends and see what happens. Also try leaning forward as you go over waves into the wind and lean back when going downwind. The Expedition Single also responds well to leans. A little twist of the hips as you push over the chop may be all it takes.