We live in a rural area with lots of trees. It's a simple fact that when it turns cold, those mice are coming inside. We've had RVs for over 35 years. I use a combination of controls, mouse traps, poison and even one of those ultrasonic thingies. Yep, peanut butter works best for trap. I use the non molding poison from Tractor supply (Tomcat® All-Weather Bait Chunx, 18 lb. Pail of 1 oz. Chunx - Tractor Supply Co.
). Don't know about them going outside looking for water to die. I don't really care because we are not in the camper during the winter. Also, we really give the kitchen area a good cleaning at the end of the season including the pantry. Also, remove your dish clothes because mice love to get in that drawer because the clothes retain the odor of food. Lastly, for some reason, some mice love some soaps. So we pull all the bar soap out of our RV over the winter. Also, watch out for squirrels...tree rats with long tails. They will get in places you don't want them a do a lot of gnawing damage. Pellet gun works good on them. Good luck.