Farmed for 45 years. Used a lot of poison that did not work. Cats did not work. One older man I farmed for used Purind rat poison. It would imbalmb the mice, they would go looking for water and would leave the barn. Thus no smell. Purina does not have this anymore. Do a search as another company started selling it. Still you need to find the holes. One post said go out at night, turn lights on in trailer and crawl under neath and in storage compartments. You have a hole somewhere. You will have a problem in CG as well until holes are found. A mouse can enter very small holes. Good luck.