Here's the way I did it and I think it works very well. I'm not sure where I saw this but I can't take credit for it. (Actually I saw most of this method on Cape Falcon Kayaks website)
before skinning the kayak I did drill holes in the gunwales just back from the stem, but after skinning the kayak I couldn't locate the holes so I had to redrill after the skin was put on.

I used a hot nail to melt a hole in the gunwale just back from stem. This kept the nylon from fraying where I drill. Then drilled a hole in each gunwale. Using a coat hanger I attached to the rope to pull it through the holes. I then used 2 wooden balls with holes drilled through the middle. Brought each end of the rope over the deck and then pulled each end through one ball then through the other ball, then knotted the ends of the rope. The balls sit on the deck of the boat and the knots are on the outboard side. By pulling the wooden balls apart it tightens the loop or if by pushing the balls closer together it loosens the loop. It has proven very strong and the balls are large enough that they make it easier on the hands when I am carrying the boat.

I then filled the hole around the rope with silicone and don't seem to have any leak problems.

I'm sure this explanation is confusing so I'll try to get a picture of my handywork. I originally used rope but have since switched to oil tanned latigo and like the look of it better.

: I've built a couple of Yost-style kayaks (Sea Flea and Sea Tour
: 17R) so far. I've mounted D-rings on the bow using bits of
: fabric glued on top for the deck rigging. Typically for towing,
: I use the deck rigging for towing. On my daughter's Sea Flea and
: mid-40 pound weight, it hasn't been an issue. On my boat and my
: lard-*ahem*, I'm concerned about the amount of pull on the
: fabric.

: I've seen nylon skins and others with the toggle/deck rigging go
: through the skin + through the gunwales. I've got some excess
: plywood up at the stem that I'm fairly certain I could go
: through safely. I just can't envision how to put an attachment
: point through the stem for towing. Ideas? Thoughts?

: -Ddoug