Tab 360 Hot Water Tank

"35" is not freezing.  The trailer will be fine...as long as that forecast you are reading holds true.  The only real answer for your trailer, or any trailer, is you must know when and why and how to winterize the plumbing.  Winterizing is always better than worrying, and the "blow out" method of winterizing will allow you to drain the trailer, blow out the plumbing with a compressor, use a minimal amount of antifreeze, and let you de-winterize quickly when the weather improves.

Do you have the Nautilus Manual?  Have a look at it, and you can see how simple most of this is to do.  

There are plenty of threads on what compressors to use and the basic process.

Here is the manual.  Take pictures and show us the workings of your trailer if you can, we would love to know more about how these setups work.  And, please ask questions, anything you can think of.  The process gets a bit bewildering the first time you stand there trying to sort it out!  We have tons of threads about winterizing and the Nautilus.