Got mice try this

Keep brush and grass away from your trailer. Ours have been stored on a gravel pad next to our garage for nearly 30 years. No brush or tall grass, or anywhere for mice to hide from preditors. They don't like being out in the open. Never once had a mouse in any of our trailers. Our gargage gets mice all the time. They were even getting the wall of our house which is shared with the garage until I sealed up every crack I could find.