In the weather conditions you describe, I wouldn't expect any problems. It would have to stay below 20º or more day and night before the cold would penetrate into any spaces.
I'd suggest you install a remote wireless thermometer in your wet bay to monitor the temperature in there. Perhaps have a couple of incandescent bulb 'trouble lights' ready to turn on if it gets colder than you predict. I also believe in having a ceramic heater or two in the RV to supplement furnace heat.
Moisture and condensation are the biggest issues in an RV in cold weather, use fans to blow areas dry and keep a roof vent open a crack to reduce humidity build up.
Don't leave water hoses hooked up, they are a pain to defrost when they freeze up. Also if you leave your stinky slinky hooked up, only dump when full so liquids flow all the way out. In summer you might leave grey tank valve open, but in Winter I'd let it fill up before using it to flush out the drain line.