After you thaw out... if you plan on RVing in cold weather, I would purchase on of these
HDX 75-Watt Incandescent Trouble Light with 25 ft. cord-CE-425A - The Home Depot
Use a reglar, old-school incandescent light bulb, and hang it in your water bay over near the pump and plumbing. It should produce just enough heat to prevent freezing, but florescent or LED bulbs won't work for this purpose.
Also--plug the area where your sewer and fresh water hoses enter your water bay with some old towels or similar to prevent cold air from entering.
Also--either purchase and use a heated fresh water hose, or use your on-board water supply (i.e. no fresh water hose).
Finally... since water will freeze in your sewer pipe too, I would not leave your gray tank valve open like most people do in warmer weather.
This video does a nice job at explaining some of the above, plus more...