Towing a whaler is borderline foolish in my view, because they are so damn heavy (and I love whalers for that reason, because they are stable platforms for working around boats.
Generally, you want the boat quite close or quite distant in towing situations. A Dinghy Tow is thus the choice of inflatable owners for this reason, but that's not possible or desirable with a whaler.
However, if you are determined to wreck your gelcoat, I would have three lines: a bridle to two D rings, one either side of the bow and a nice big, slightly slack poly line to a stem fitting on the whaler. The bridle will take the main pull, and, should you encounter cross currents or winds, can be tightened and slacked as needed to correct tracking problems. The big center line is a backup. You'll want chafe gear at the stern that won't allow the poly to heat up and melt as the friction energy of shock loading is converted to warmth.
Really, choose the foredeck. I don't know what a 12 foot whaler weighs (500 lbs?) and I know it's going to be a bear getting it aboard, but towing it in anything bigger than 2 foot waves is problematic given its inertia.
