kayaks are not designed to be towed
so towing at a pace faster than another paddler would go is sketchy at best
also keep in mind other than river play kayaks
most kayaks do not have planing hulls
and you definitely do not want the kayak to nose dive under the water
with that said
I've towed kayaks 4 or 5 miles at times in order to allow paddlers to go further out
and it took forever because I never exceeded displacement speed
nonetheless, it was about twice as fast as they would have paddled out
and they were not already tired at the point I dropped them off
I've towed with my inflatable using the rear carry handles,
set up in kind of the reverse of how you are supposed to tow an inflatable,
with a slip bridle. A float at the slip ring will help keep you line out of the prop.
my transom launch wheels struts and attachment are probably strong enough
to tow off of, but i have yet to try towing anything off of them
good luck and let us know what ends up working for you