You might want to use hot wire if you have foxesI put it on the outside only because of a video I saw of a coyote jumping and pushing on the side walls of a run trying to get in, He was really banging it up and putting a lot of pressure on the HW cloth.
It's my thought that with it being attached on the outside the stresses are more evenly distributed along the whole length of that surface whereas if it were attached on the inside the stress points MIGHT be more constricted to the actually screw/staple or whatever attachment point.