Hook for Kayaks

I have no experience with kayaks, and no recommendation for securing one to a Prius, but I would note that the hook that comes with the car—called a “towing eyelet” in the Owner’s Manual—is Toyota part number 51961-47010, and the U.S. list price is $42.15; a Toyota dealer near me sells them online for $29 or so.

As seen in this part of an illustration from Toyota’s New Car Features book, for aerodynamics, the car’s front lower surface is almost entirely concealed with plastic covers, making it difficult to access the body structure:

I wouldn’t attach anything to the fasteners holding the covers in place, which presumably weren’t designed for additional loads. Many of these are just plastic clips, anyway.

 

I transport my kayak on my roof rack without tying front or rear, just strapped onto the two kayak carrier bars. But maybe my kayak isn't as long as yours. Mine certainly seems secure enough that no way would additional tie downs be needed.