I have lots of mice and rats around. We have pets so we can't put out poisons. I bought 4 of the electronic rodent deterrents shown in the link below, and have one in the garage, two under the truck where my truck camper stays and one plugged in under the porch. I didn't have a problem with them in my tc, but they would get under the truck hood, etc and chew wires. They have been remarkably effective. I haven't seen one rat/mouse dropping in the garage since I've been using these. They only get a 3 star rating, but for rodents they seem to work great.
https://www.amazon.com/gp/product/B018FDB33Q/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
