In Northern Canada we rarely attempted to start anything without the engine being nice and warm with either a 'tanis' type heater or an electric car heater fan placed in the enging cowling. Engines were always covered with a blanket. I do remember once trying to start the islander when temp was a WARM 0 degrees C, and no luck what so ever. Put a blanket on it and a car heater inside the cowling, and we were in business.
Oil temp is an issue for obvious reasons. Another reason that was explained to me (not sure if true or not, but makes sense) was that Moisture is a natural byproduct of combustion, and any moisture that was left in the cylinder would turn to frost on the cylinder walls (causing wear) and most importantly for starting, on the spark plugs fouling the plugs, and thus not giving you any spark. Your best bet would be to be sure the engine is nice and warm (above 0c) before setting out for your adventures. Flying in the winter is great... Much greater performance at -30c then at +30c!!!
Have fun.
Yoohoo