When sleeping in the back of the Prius, the key element missing is a way to open a closed hatch from the inside.
To install, remove the inner plastic trim on the vehicle, and un-plug the connector from the OE switch. Plug in new harness to OE switch and OE switch connector.
Drill a hole in the hatch plastic inner panel that’s removable in the center of the rear interior hatch. Install the switch and re-install the inside hatch plastic trim panels.