Sail boat towing other boats (similar loa) should attach towing line close to her center of effort. Think like attaching towing line to the mast foot. Not on the stern. Not an easy task to do. That's why many sailors just use any stern cleat. And the towed boat should attach towing line not to the bow, but also to the center of effort. Then both boats can manouver. I also lost rudder blade, on the 10m sailboat, in the middle of Adriatic sea, 2005, during regatta, in 35kt NE wind and 3m waves. Not possible to steer anyhow. Tryed to improvize rudder, but we almost lost a crewman. We were on 2nd reef already. SAR came. Since there was no rudder on my boat, attaching towing line to bow was only option. My towed sailboat course was changing +-30 degrees every few minutes, and finally towing line broke loose because of the forestay chaffing.