I've been entertaining the travel trailer idea myself. In fact, after I recover from my surgery, I'm going to build a "bug-out trailer" from a 5x8 enclosed cargo trailer for weekend jaunts and church work. There are some really neat ideas on YouTube; but I digress.
I knew some folks that lived for several years full-time in a decent fifth-wheel travel trailer in Mantua, OH. Since they lived in it, they didn't have to "winterize" as they would if they were going to store it. In a cold climate I'd venture to say that the precautions would be the same as a mobile home. You'd want to put heat tape on the water lines and possibly the drains. I think they had some sort of heaters in the storage tanks, but since they were static they kept the tanks open so they'd drain directly to the sewer connection.
Also, if memory serves right, but I think he added a little extra insulation under it since they live in a cold climate area; it's probably similar to where you live.
These might stimulate some thinking: