You do not want to connect the tow line to the mast of the towing vessel, please. The tow line is under stress and subject to breaking (say you were towing a 35 foot offshore fishing boat in seas with a 3 foot wind swell and an 8 foot ground swell...maybe enough shock load to break 1" nylon?). If the tow rope breaks it would be likely to come back through the cockpit, perhaps removing a head or something else still unpleasant.
Connecting the towline to the mast of the towed vessel is a choice, but I've only done so when the towed vessel lacked suitable bow cleats.
Certified...in several regards...