A cat, if it can get to them Doubt it can climb inside the walls though.
i know the black racer idea makes women and feller cringe but if you can get a young one they train rather easily. They are intelligent and they love rodents.Releasing a grown one in an RV will do the job over a few days, perhaps.
Then you gotta catch the snake. They will bit but have no teeth just a hard sharp mouth edge.I've been bit more than once by different wild snakes. usually get control of them first though. Look at it this way you can't have a snake story unless you catch one or one bites you.