I guess if I were to rent a Kayak I would haul it off and not tell them what I was using it for.... If it drifts off because you did a poor job anchoring it, you pay for it. I cant imagine that they could actually regulate such a thing
The problem with all of these rental places is that you can't "haul it off." They don't let you load the kayaks on top of a vehicle-you have to launch from the front of the shop.