Q:”fresh tire tracks serpentined back toward the hopper“, in this sentence, in what position is the speaker and the hopper?

In this case, a hopper most likely refers to "a funnel-shaped chamber or bin in which loose material, as grain or coal, is stored temporarily, being filled through the top and dispensed through the bottom." The speaker is standing at some distance from the hopper. It isn't specified that he is going anywhere - he is merely observing that the tire tracks are sinuous and stretch between his current position and the hopper. "Back towards" only means that, as he is looking at them they go into the distance (whether or not the vehicle that made them was travelling in that direction). It would probably be clear from the context of the rest of the story whether the vehicle that made them had actually been travelling towards or away from the hopper. Because only the tracks (and not the vehicle) are mentioned, one would assume that there is no vehicle in sight.