I think this is the key. 10 km can be walked with your bike in about an hour, maybe 90 minutes. If you can walk, you'll need to stay alive that long. Some food, decent clothing, and those hand/foot warmers should be enough. If you're injured to the point where you can't hike out, that's another story. At that point you need to bundle up, eat some food and wait for help to come by. Changing a freehub body by the side of the road would suck enough that it wouldn't be worth it unless you had the time to kill.