Good idea to camp in sub zero temperatures?

This weekend I attended a larp event in a reproduction Viking village full of poor fitting shutters and draughty thin walls, I was not expecting to be warm but was sufficiently comfortable to make the whole event very tolerable.

On Friday after a very wet start, the skies cleared and the temperature dropped overnight sufficient to freeze the puddles so wearing my thermal underwear I tucked myself away in a 3 seasons sleeping bag, fully enclosed so only my nose was exposed, then covered in a 2nd sleeping bag and blankets I managed to feel cosy enough to sleep.
So I slept about 4 hours until around 5am when my bladder became desperate for the loo, surviving another hour I resisted the bitter cold I could feel outside my warm world but could last no longer, so in thermal underwear I left my sleeping bag found my boots in the dark and walked to the loo and back over frozen mud.
By the time I returned my bedding was cold and I could not warm myself back again to feel comfortable but stayed in bed till just before 8 when Julie got up, put the kettle on and started a fire.

The only other side effect of the cold was the butane gas preferred to stay in liquid form in the can so barely produced enough heat to boil a kettle, solved by putting the cans under my clothing and swapping cans between uses.

The rest of the weekend was slightly warmer, and we also discovered fire in the huts which although very smoky and needing a shutter open to create an air flow warmed the hut a degree or more.

The event itself was good, a good main plot that allowed for plenty of skills to be used, overall I enjoyed myself. There where plenty of players new and old, and chance to pass on various pieces of information gained during downtime.
It felt a little strange to be there as player not ref, but I quickly got over it although still wished at certain quiet moments to get in there and move things along, finish odd plot areas that were left from the last Strangehaven event, although if numbers improve for the site as they did I've been told Strangehaven will probably re-start for 2009.

On Sunday I got back home to a pile of cardboard litter and brown gorilla fur created Jasmine as a present to impress Julie and Dave who stopped for a warm drink or two on the way home.
I was very tired by then, and Julie looking particularly sleepy and she had another hour and half drive, so after a shower and food (baked potato and cheese) I fell asleep on the sofa with a cat asleep on my chest from around 8.30 until 11.30 when I found enough energy to relocate to my bed.