I live just south of you in Mount Vernon. Put some of your hay around the trailer like a foundation. You might even put some plastic over it to keep it from getting soaked (it rains up here, doesn't it). If you get it mostly sealed off you'll be fine. Throw a 150W light under there and turn it on if it's going to get really cold (below 20F). That should take care of any freezing. Definitely heat tape your water hose. But remember, critters like that warmth under the trailer too.
"All fisherman are liars, except you and me, and I'm beginning to wonder about you.