Is it possible to add an aftermarket rear wiper to a 2013 Hyundai Sonata hybrid?

The expense would be ridiculous. It would probably be easier and cheaper to replace the rear hatch with one that already has the wiper and motor, then add a custom wire harness and replace the multifunction switch, then reflash the body control module to include rear wiper functions. Your existing body wire harness does not accommodate the rear wiper, so you can't "tap into" it, you would have to run your own wiring for the control circuit as well as power.

Rats. I was afraid of that. Thanks so much!