I can't give you specific info on the FJ's, but I've seen a lot of dinghy-type boats (especially planing hull boats) with fairly large holes in the transom. In fact, other versions of my Albacore have pretty large (look to be at least 3x5) holes that are covered on the outside by somewhat stiff plastic sheeting, like you'd fine on the cover of a school notebook. When water gets into the cockpit, the force of the water causes the plastic to deform, and creates and opening through which the water can escape. By contrast, if you were in a following sea and the wave came from behind, the force of the wave causes the plastic to press against the hull, helping to seal it. Obviously, this isn't fool-proof or leak-proof, but I've seen it done. You can see them in this video:
Hope this helps!