This is what Bman did to his WSM. I copied it and works great. I guess this could be applied to a kettle too.
That's what I'm planning on doing, only to my damaged lid. Any tips on cutting the notch?
Some use a Dremel with a "cut off" wheel.
You have to drop in twice and clean up the bottom of the cut though.
I would use a "peanut grinder" (4-1/2" angle grinder) and a stone of the width that I want the notch.
You would just drop in once and the bottom of the cut would be done as well.
I have often thought about applying the Nomex gasket to the underside of the lid on the kettle and leaving a short gap where I want to run cables. Possible no-notch solution.