I've heard of a lot of people having electrical wires chewed on by mice too. So far I've been lucky.
Back in the late 80's we went to get the combine ready for harvest and found we had electrical issues. I drilled out the pop rivets on a corner piece in the cab to check the wires. A bundle of over 100 wires that went from the side counsel to the overhead counsel with all the gauges and more switches. The mice had chewed through all the wire loom, almost all of the insulation, and about half of the actual wires. Four days of spending all of my free time cutting, soldering, heat shrinking, cutting, soldering, heat shrinking, cutting ...
To make the job as easy as possible, I made a template eight inches long, cut that length out of a wire, stripped the insulation back on each end, had a pre-cut fill in ready, soldered the connections, and protected with heat shrink tubing. Something I was smart enough to start with was staggering the splices up and down. This is how I came up with the eight inch length. I based it on the length of damage and getting staggered joints. I figured that If I just lopped it all off at the same place I would never have room for the thickness of the splices.
Best feeling, besides buttoning it up after many many hours of work, was going through harvest with all gauges, monitors, lights, and switches working properly.