One way you can get rid of that chicken snake is the same way we used to get rid of them in the chickenhouse is to get some porcellan eggs and set them in there. When it swallows them, it cant squeeze them and break them and it winds up killing it. Just a thought but better check the camper because if it does that you may find not only a snake but a VERY stinky one. Also one way I have heard to get rid of your mice in the trailer, if you dont want to use poison, is to get a bowl of dry mashed potatoe flakes and put them next to a bowl of water. The mouse will fill up on the flakes and then drink the water. The flakes expand and it dies. Either way if you dont keep a watch you will wind up with a stinky camper.