Charge Disconnect Alarm?

I have completed my Plug-in conversion DIY installation and have also installed the standard SAE-J1772 PEV connection cable so I will be able to use the Level 2 public charging network stations. Myself, I have no reservations about this other than a warning from my son, who drives an Leaf which will notify him by phone if someone tampers with his charge connection. However, if I am charging for a couple hours I don't want to come back to the car and find that someone couldn't wait and removed the plug and began their own charge. (not sure it they could do that on my account card or not, but that's not my point.) It's the 2-3 hour of delay in my trip that would be lost.

Here is my question, in the interlock device that is part of the vehicle receptical installation there are are Normal Open and a Normal Closed contacts provided for other possible functions, which I am not using. What I would like to do is utilize one of these to trigger the vehicle's alarm system. The most likely place to do this is the rear hatch/lift gate latch, which would normally trip the alarm if it were opened when someone without the keyless FOB or key isn't present.
From the manuals and wiring diagrams (just block diagrams rather than schematics) it is difficult to determine which wire might be the correct one to wire into one of these module terminals.

I could eventually figure this out but first wondered if this would work or is there any other method that someone might think of??

Opinions, thoughts welcome.

Steve