Wile I haven't had issues with the trailer, I did get them in my house. I live out in the country surrounded by fields, and those buggers found a way in and embedded themselves in the wall between the kitche and den. I tried glue traps, peppermint oil, made the house smell nice, but did nothing to deter them. I finally discovered electronic mouse traps. They have 4 AA batteries, and a lid. You open the lid and there is a pathway to two metal plates and a bait area. I put some peanut butter in, closed the lid and set it where I saw a habit trail. About 90 minutes later I hear a Buzz, thump. Caught one, instant kill. Dumped it out, 10 minutes later, got another one. By the end of the night it looked like Mouseaggedon in my trash compactor. All told in a weeks time the traps got 23 mice, and haven't seen one since. It was a Mousacre.
Get one if you have mice in there, set it up where you suspect they travel and put some peanut butter in, and check it every so often. Kills them instantly, they have no idea what happens, just ZAP!