stof -
I get (kind) of what your saying, but here's what I can see from my research:
Space is a great insulator of heat. If you were to magically become exposed to space, you would not die from thermal problems, but atmospheric (or the lack of it).
So as you stated, the only way heat would be transferred to the dark side would be that which heats the planet's surface, then radiates through the ground to the darkside.
Such a band would probably be very small, and get progressively colder, very quickly. However, it may provide a small band of a very temperate area. Nothing that would make for a fantastic voyage, but could maybe support an underground network of habitability along that area that would be between 0C and 50C.
Back from the dead, I'm afraid.
