This is what i use for my Towee and it works really well, you can probably down size it for a canoe or Kayak.
Carabiner attached to Heavy duty Bungee with S hook, gives a bit of "shock" absorption if it snags a little, (so it doesn't throw you on your a#@!!!)
Attach other end to boat fender with "zip ties" These will break away if hung in fast water.
Attach heavy rope to other end of fender, and then another caribiner to other end, this allows you to change out chain sizes.
If "Zip ties break away fender will float allowing for retrieval.