I tow cats sometimes at speed to check out the foils- like the one pictured sailing in this thumbnail. It works fine to tie a light line around the front crossbar on one side, through a small loop of line on the bridle tang, leaving extra to form a bridle, then return through a loop on the other tang to the crossbar. The towline is attached to this bridle with a bowline knot. Then have a kid wearing a lifejacket steer the cat? The kid will love it, and you can go Really Fast if you really have to. But seriously- towing at 12-15 knots works fine and isn't too fast.