The answer is... it depends.
Your pipes are not going to freeze at 32 degrees but if it's going to remain below freezing for several hours or days, you could have a problem.
The 'easiest' precaution you can take is to drain the water lines, open the faucets to allow warm water in and expansion in case the water starts to turn to ice. Open the cabinets near the plumbing to allow warm air near the pipes.
Remember that running water doesn't freeze. So if someone gets up in the middle of the night and flushes the toilet and runs the water in the sink, that will probably keep the lines from freezing in a light overnight freeze. At least that's worked for us.
However, many of the lines are under the rig or in the walls, so if you're going camping in 27 degrees for more than a day, you might want to consider winterizing or at the minimum, drain the lines.
2015 Dynamax REV 24TB class C