Emergency? I have routinely carried 2 kayaks and have never needed an extra connection other than the roof mount. For piece of mind, the hood hinge is available, near the base of the windshield. That's much easier to access anyway.
Also they have nifty simple little hood tie downs on Amazon. i think it fits in the little gaps where hood meets the body. Never really heard of using the tow clip on a Prius. I usually look for something underneath...Gen2 has big eyelets down there underneath the head lights, but I don't know what other model years have. ...for Prii or general cars, have you seen this?
Pictures of this Gen 4 Liftback look like they are using the front tow eye. Rhino Rack Vortex 2500 Cross Bars | PriusChat