Not sure I have a correct picture of your situation so this idea might be wrong.  All I know is that mice do not chew on things that are greasy or oily.  For example, often mice chew through the corners of a garage door, on the rubber or on the wood.  Simply take a paper towel or rag, soak it in oil, squeeze it out.  Roll up the towel to make it long.  Lay in the corner and close the door.  Might not look pretty, but they will not chew in this area.  I do the same for electrical wires on motors.  Coat them with grease.  No more chewing.  Hope this helps in some way.