I am not sure of any rubble in the sound in Navarre but there is the Capt Bob Quarles reef which I believe is bridge rubble. Its in the sound directly behind Chicken Bone Beach where that old boat ramp use to be years ago. Its shallow, like in ten feet of water or so and I believe its marked by a buoy and or some posts. Its been there a couple years now, might be holding some mangroves.
Ive never heard of anyone fishing it though.