Another "but" would be that, even if you do ALL the prep necessary (and it sounds a lot like Scott getting ready for his Artic Exploration), you are then stuck to the trailer.
In other words, if you go away for the weekend skiing, and the furnace happens to get blown out by a capricious gust of wind during a cold period, you could come home to something resembling Superman's Fortress of Solitude (all ice).
Nobody has mentioned the humidity issue: a human gives off a lot of moisture just breathing and perspiring, and with single-pane windows, you will have frost to an interesting depth on your windows, unless you leave a window cracked open a bit.
To sum up, it IS just possible, but ask yourself if you can imagine yourself dedicated to making it work, because if you aren't, it could become a very unenjoyable experience fast, should something go off the track...
If it's to be, it's up to me.