In what conditions should I start to worry about freezing weather causing damage to hoses and other components?  I've camped with the trailer still winterized when I knew I'd be in freezing weather all night long and part of the day.  Sometimes, I have freezing weather at home, but not where I'm camping so would like to use the plumbing.  Should I worry about it when I'll be in freezing temperatures for a few hours overnight?  Are there things I can do to keep vulnerable parts from freezing when I'm in freezing weather?