I think this is going in the right direction. This scenario necessarily involves temporal markers 'when', 'has (travelled)', 'was', 'then' etc, and the notions of signals and 'simultaneity'. If you follow through long enough, you will have to deal with time. Einstein also had to wrestle with such things and the whole thing was inextricably entangled in time. At least that's an impression I recall when I went through his little book on SP years ago.This is all getting very confusing very quickly...regarding defining movement without an implicit involvement of time however, how about this: when my car has travelled X meters, i measure the distance travelled by a ray of light which was emitted as the car started to move. My car would then have travelled an equivalent Y meters of light. This is how I would think of doing it since light is my absolute displacement reference.