Reddit reviews Raco 8660, 1

You don't need the fancy box for outdoors. Just a basic single gang metal box like this example from Amazon would work, assuming you can get it in and out. If not, you could remove the bracket and screw through the box itself into the stud. Here's one without the bracket, but it's meant to be screwed through the back into wood. You'd have to drill a couple small holes on the right to screw through the box into the stud on the right. But if you can get it in there with the bracket, that would be better. You can find these at most any home center as well. You can attach the transformer to the box first to see how big the hole in the drywall/plaster will need to be, then you can enlarge it before getting the old one out allowing you extra room to maneuver.

in this situation pest control is only money wasted, if you get rid of these squirrels others will move into this territory.

The only hope is to enclose the cable in something that they can't chew through. Don't know if soft wrapping will help, but it seems that if it's soft it will be great for a nest too.

for the thicker parts with jumper cables I would use something like this:
https://www.amazon.com/Hubbell-Raco-8660-Single-Handy/dp/B000BQL3OU/
with a cover.