We are wintering for the first time and have really found this forum helpful.  My RV dealer had some great suggestions for us.  
We put a little heater in the storage unit of our fifth wheel plugged into to a thermostate controlled plug in.  This has helped with keeping the pipes warm.
We then purchased a hose that is heated.  This way we did not have to run any heat tape or wrap it.  It was actually designed for farm use but if you buy a couple of couplers to reverse the ends and it works great for the fifth wheel.  It did not work the first week because I had not reversed the ends so the sensor was up in the fifth wheel and it was staying warm.  Once I reversed it we have not had any problems.
This week will be our biggest test because we are supposed to be 8 degrees below tonight with 30 mph winds and 6 to 8 inches of snow.  If we make it this week and know that we will winter camp again next year.
Thanks for all the advice.