That looks as a very clever system. I suppose you can lift the fish up to the pulley and then swing the 'crane' backwards to get the fish over the outboard engine and into the boat? My 'system' is not that advanced, in my smaller boat I use a fixed wood plank with a pulley. The plank sticks out horizontally behind the motor and I need a stick to press the cables with the towfish from the pulley. A bit clumsy, but it works.
On my large boat I simply deploy the towfish from the side of the boat. When towing the cable is routed one turn around a pulpit post at the starboard side and secured to the deck with a clam cleat. I use a PVC coated steel wire for towing and the ethernet cable is just attached to the wire.
Rickard