We went out a few times in cold weather in our previous trailer and while smaller, I think the same condensation effect is universal. With our Aliner the extruded aluminum edging would be where the condensation would build up the most. Caused by us breathing our warm moist breath all night agaings the cool outside, and especially those aluminum members that were colder...just like a cold drink on a warm humid day. What helped us is cracking the roof vent a touch, and just having a handful of microfiber towels to give it a wipe down in the morning. I think as long as you dry it off, it won't hurt anything...if you're cozy and comfortable I say go for it! Plenty of people winter/cool weather camp in tents and canvas pop-ups and get the same condensation issues.
And as Tobor said, the water system would be the biggest concern if the overnight temps are below freezing. If you really wanted to, you could insulate the tubing and get a tank heater pad to keep from freezing up, something like this mod:
http://www.modmyrv.com/2008/07/17/rv...k-heating-pads