1) your in a trailer so you should have zero windchill factor in the treiler.
2) Just bring a few comforters, quilts etc... and if you need them use them. You really have no limit to what your caring if your bring a trailer.
3) Get some kind of 12volt heater and you can use it to warm the trailer up a few degrees, or a 12/120 inverter and use a standared home heater.
4) Even in negative degrees out side in a trailer you should be find.

Cheers

I had a cot that I used in all seasons. Great in the spring / summer / fall because of the air circulation underneath. Bad in the winter for the same reason.

During winter camping in New England (5 - 15º F), I tried using space blankets between the cot and bag. No help. A ThermaRest pad was better, but still chilly.

Some of our guys used air matresses and froze.

I finally used a strip of carpet and my ThermaRest on the ground and slept well.

From my experience, sleeping on a bare cot and sleeping on the bare ground are the same -- they both suck heat out of you.

Either place, put down a piece of Reflectix flexible insulation (that mylar/plastic laminated stuff from the hardware store), and then a closed-cell foam pad on top of that, and you'll be fine.

And if you're sitting around a campfire in a folding chair and your back is freezing, grab that Reflectix, fold it in half, and put it under/behind you in the chair. Toasty.

Sue

Oh yeah, I forgot about the chair insulation. I found even several layers of corrigated cardboard put on the seat can make all the difference.

At some point I'll cut up a cheap closed cell foam pad to chair size.

Having slept on a cot at 10,000 feet during an Elk hunting trip to Colorado for 8 days in November of 2005, I will say it can be done.

Once I set the cot up, down went a closed cell foam sleeping pad (the cheap ½ inch variety). On top of that went an old wool blanket I carry around with me. My sleeping bag is an old 2 part army surplus sleeping bag and inside that went a fleece liner.

At night I would heat up water and put that in a 32 ounce Nalgene bottle and threw that into my sleeping bag about 30 minutes before going to bed. I wouldn’t waste the water, but rather drink it the next day. I would then change into long underware that was used for nothing but sleeping to ensure dryness. However, I did notice that my legs got too warm and sweat a bit on a couple of night.

DO NOT forget to wear a good stocking cap at night when you sleep. One night it fell off and I swear someone dumped a bag of ice into my sleeping bag.

A tip I used and the other guys wish they had thought of was the use of a "pee" bottle. I use a 32 ounce wide-mouth ;-) Nalgene bottle with the YELLOW cap. I keep it next to my cot when I sleep and instead of having to completely get out of my sleeping bag and go outside to urinate, I simply rise up to my knees, use my pee bottle and then lay back down. No boots, no tripping over gear, no fumbling for the tent zipper at 2:00AM, no freezing your tail off going outside in freezing temperatures.

Regards,
Steve

I've never slept on a cot while camping but I do use an air mattress every time, my tired old bones need the cushioning.
A few years ago while camping in PA during Oct (tent camping) it went down to high 30's over night. I almost froze. Actually woke up shivering. I had mistakenly packed only 2 of my summer sleeping bags. I had one under me and one over me with a wool blanket over the sleeping bag. 2nd night in the ten with same temps I put woll blanket ontop of air mattress, sleeping bag on that and had only the other sleeping bag on top of me. I slept like a rock.
Lessons learned:
1) make sure to take proper sleeping bags
2) have twice as much under me as on top of me

I recently returned from a car camping trip where the low was 23 degrees. I used a Cabela's army cot, a 0 degree mummy down bag and a ThermaRest self-inflator. Now, I'm a cold sleeper, so the rating for the bag was more like a 25 degree bag. I slept warmly and comfortably.

I think what made the difference was what I wore while sleeping.
I had "expedition" weight thermal underwear, wool hiking socks and, most importantly, headwear. I brought a watch cap, a heavyweight balaclava and a lightweight balaclava. I brought these because I did not know what I would encounter- you never know as I was in the High Sierras. As it turned out, all I needed was the watch cap. With this set up, I didn't need to cinch up the hood to my bag.

The balaclavas cover pretty much your whole head. My heavyweight version covered my head with the exception of my eyes; there's flap that covers my nose and there's mesh over my mouth.

Having the insulation under you is very, very important as pointed out with other posts. Minimally, I suggest a closed cell pad (such as the Ridge Rest); but a self-inflator AND and closed cell would be ideal. I would put the closed cell on top of the self-inflator.

Winter camping is awesome!