I added a sub fin and water rudder complete the conversion as seen below. I am a firm believer in the K.I.S.S. principle as can be seen in the pictures of my water rudder. I used a .40 size Dubro tailwheel bracket, a piece of pushrod wire, a 2" piece of outer pushrod sleeve, and some duct tape. The pushrod sleeve was attached to the bottom of the rudder using a couple small pieces of Ultracote and this holds the wire to the rudder. I then bent a triangle at the bottom of the wire for the rudder and covered it with duct tape. I do it this way so if I need to make adjustments I can remove the tape, rebend the wire as needed, and reinstall the tape. Easy peasy.