[Scott-PA]

Hey Cal, not sure if you would entertain this idea but after you splice in a longer section of wire a small shot low expansion foam (Great Stuff style for windows/doors) might help to stabilize the wires and prevent any additional cutting/rubbing of wire insulation.
You obviously have done more than I thought of, so at this point all I can add is spray foam to stabilize (low expansion type).
Good luck my new friend!