Hello Luke. That looks ok, a floating line is a good idea when there is an outboard engine involved. You will want about 15 metres or so in order to keep the towed boat at a safe distance, but still be able to shout to the crew of the tow.
Looking at the use for this rope it is suitable for sheets so it is low stretch which can give you problems with jerk, enough to be uncomfortable at best and putting a high load on your attachment point, which should be bolted through the transom with a spreader plate to avoid damaging your own boat.
I made up this snubber from a loop of shock-cord which I then folded into a further three loops (the photograph shows it better than I can describe it) with a snap shackle in one end to clip onto a D Ring bolted through the transom above the tank on my old Mk2. I used self-amalgamating tape to keep it in shape.
The towline is attached by a bowline to the other end of the snubber. It means you can motor away from your tow secure in the knowledge that it won’t jerk your transom off.