A common enough problem. Ask over at dpreview.com
For battery life, hook up a two chargers in your truck, mounted some place semi-permanent, and always keep batteries in them. this is for one camera. Which battery does teh GL1 take? For some reason I thought it was the same BP511, but I'm probably wrong. Keeping the batteries in the charger will keep them warm and ready as you know the charge drops off fast in the cold.
Or get a small insulated sack and put a hand warmer in there with the batteries. Or boil water and pour it into a stainless water bottle and do the same. that will keep them warm.
A mentioned, keep the camera lens cold. But not neccessairly the camera. Some sensors don't like cold.
There's probably some sort of camera muff you can use for the GL but anything for a Canon D would be bulky.
Lastly, consider keeping the camera on he outside of the truck, maybe in a pelican, while driving in low crime areas. At night, put it in the truck for safe keeping or your tent. Keeping it on the outside will keep it at the right temp. Even if you kept it in the fridge inside the truck, you stand a good chance of catching condensation on he lens when you move it from the fridge, through the heated cab, to the outside. if the truck cab is always below freezing, then it's not much of a worry.
