I noted two years ago our most frequented camp ground had some camp ground cats.
So long as they don't get fed too much they keep the ground squirrels and mice cleaned out or a t least thinned down. A lot of busineess have pet cats that patrol the stok room and floors at night.
First place to start though is keeping them put. Light inside, spotter outside, at night front to back. See a hole use foam. there are two types of expanding foam. One fills small holes and the other one big holes. Mice don't like the stuff. Rverse the process and flaslight and daylight into the darkened interior.Seal up any more holes or caable runs and compartment gaps deal with.
Spray the whole bottom with paint with a lot of fungacide and bu killer mixed in. Home Depot sells the tubes of them. Just dump in the paint and mix.If you used something like Gatorhyde, or truck bed coatings and the fungacide and bug killer nothing would want to chew though if they could.