Since this simple cable my just save you some day, think through the worst case situation on what fails when. As the others have said, it should attach to the truck separate from the hitch, receiver, safety chains, the 7 wire cord etc. Ideal is to the truck bumper or frame.
Each TV has a different setup on how to do this. It may take a little thinking on how to create the attach point and sometimes a small chain and carbiner can help. These may help spark some ideas for you to build on. Simple, easy to connect to and effective.
Here is my current Ford setup
Here was my prior GM setup.
And while you are sorting out where to attach the cable, sort out the cable length on when should the switch activate? There is much debate on this.
See here with several links on why from years back
When to have the breakaway switch activateHope this helps
John