First I tried to do this with a GoPro and it sucked. So I just stuck a spare iPhone up there and had it take 3 photos a day for 5 months using OSnap. It only took the photos during daytime hours to keep customers out of the shot. Unfortunately sometimes the lights were on and sometimes off, so it flickers like crazy. Also I only ended up with about 3 months worth of photos, because sometimes OSnap would crash at random, and sometimes iOS would decide to pop up an alert, and that made all photos stop until I clicked OK a couple of weeks later.
What have I learned? That our bar surface's unique fingerprint changes much more slowly than I expected. And that taking decent time-lapse video is really hard.