Automobile reverse sensor cutoff

A little background to my project:

I own a truck with the "backup sensors" that beep when you are within a specific distance to an object. While I LOVE this feature, I use is truck to tow often (a 16' Search and Rescue trailer) and hearing the "flat-line" tone any time I try to back my trailer up is annoying.

I have an idea I think would work to disable the sensors only when a trailer umbilical is attached, keeping then little ones safe when backing out of the driveway and keeping my sanity when backing the trailer on a call.

My idea revolved around the ground pin of the 7 pin trailer umbilical. When disconnected, there is no current returning to ground on that wire, but when connected I should receive one of three sources of current:
1) the ground of the reverse light pin (some trailers have backup lights that get the current from the center pin of the umbilical)
2) the ground of the trailer lights (when towing the trailer we must run with our headlights on, therefore powering the running lights)
3) the ground from the battery hot from my truck (our trailers have a car battery in the floor that charges from the connected tow vehicle).

My idea is if I cut the ground wire on my umbilical, can I use that as a trigger to activate a relay that I would also connect to the ground of the backup circuit, where the backup circuit connection would usually be "on" (allowing the backup sensors to work normally) until the ground from the umbilical triggers the relay to "open", disabling the backup sensors (only when connected to a trailer).

Is this possible, and if so what do I need to do it (4 pin relay/5 pin relay, diodes, etc.)?

Thanks in advance for any tips or guidance!

Sensing current is not a simple task. You either need to place some resistance in the line and detect the voltage drop across the resistance, or use a sensor such as a hall-effect device to detect current. Either approach requires some expertise in electronics.

I would suggest as an alternate you configure a relay in a latch setup to lockout the backup sensor when you need. You would use a push-button to latch the relay and lockout the backup sensor. The relay could be powered from the ignition switch so whenever you stop the engine, the relay would drop out and the backup sensor would again be active. Perhaps a little more hassle than automatically sensing the current, but a lot easier to implement.

To use a standard multi-pole relay as a latch ,you just use one of the NO contacts to apply power to the relay coil. That will then maintain the coil power after the push-button is released. If you need a circuit diagram, I can provide you one.

https://www.electro-tech-online.com/threads/reversing-sensor-cut-off-circuit.116192/

It seems to work for me.