I am currently towing a 2016 Edge. Rather than disconnect the negative cable, I installed a disconnect relay on the positive battery cable. There is a very short positive cable that goes from the battery to the power distribution box. I simply ran one side of that to the relay and a cable from the relay to the distribution box. Simple solution. There is a button inside the vehicle that toggles the relay. I installed it in the console to avoid accidental pushing. I ran a charge line from the standard battery terminal on the 6 pin trailer connector on the car. This runs to the battery side of the disconnect relay with a 15 amp auto reset breaker to protect things. My motor Home has a relay that disconnects the charge line when the ignition is off, so the toad can’t run down the coach battery. I also power my Air Force one brake system from the battery/charge connection. That way in the event of a disconnect, it is still powered by the vehicle battery. I also used a plug and play wiring kit to enable use of the existing tail lights. You have to pull the left taillight to gain access to the connectors but that is not extremely difficult. All of this was purchased from etrailer. Be careful to specify the proper model of your vehicle as the tail lights kits are different on the platinum I have than on the SEL and sport. I ordered the wrong one the first time and had to change it. I have been on the road with this setup for 3 months now and it works like a charm. I simply go through the Ford procedure for towing, then after I shut off the ignition, I hit the battery disconnect button.
