I have had good success with 5 gallon buckets with 4" of water in them. Put a can on a rod going across top of bucket with peanut butter on it. Put a small board up to one side. Mouse goes up board, gets on can to get peanut butter, can rolls and mouse falls into water and can't get out. Recommend cleaning trap every couple of weeks so the smell doesn't overwhelm you. I put mine near the trailer (not in it). First week caught 20 or so. Not so many now. We have peppermint oil on cotton balls inside trailer that we add a few drops to every few weeks.
Just google 5 gallon bucket mouse trap for details.