I lost track of the bear... After shooting him at the Camp Office, I continued on to Frozen Creek. Strangely, he was still running away (caught against rocks) when I caught up with him there, and he didn't stop until reaching the Cabin to the west of the lookout. After shooting him here, I was tired and cold, so I took a nap and made coffee in the cabin, but I could not find his tracks afterwards. I've checked all of the other locations to no avail.

Edit: I tried another time, this time only taking 2 naps in total, mainly to get warm, and also to not lose the bears tracks. This resulted in my exhaustion bar being empty at the end, but I finished in 11 hours 12 minutes! Could probably beat it easily if coffee happens to spawn.