There is a grommet high on the firewall behind the ABS unit that you could pass wires in and out of. A couple of things to remember about doing this:
* If you make or enlarge a hole, that hole becomes a potential source of water entering the cabin, so if you intend to take the vehicle through deep water, make sure you seal it up. The Navara can wade bonnet-deep without problems and has been seen wading through water halfway up its windscreen.
* The cabin wires going to and from the switch can be smaller gauge wires, because they aren't running the power to the lights. The wires should come out into the engine bay and then connect to a relay, and the relay has to have heavy duty cabling up to the lights. The longer the distance, the heavier the cable required
* If you're running cable down and under the cabin, try to secure it up as high as possible so that it's protected from being snagged by sticks if you're off-road or wading through water.
* Use waterproof relays and GOOD crimping on the electrical connectors. The thin, flat crimping tool you can buy cheaply in most places is rubbish and won't do a good job.