Nick,
Good comment. I have also had difficulty seeing the sighter, due to the lower angle of the fall sun. Seen against a high bank of white snow, that's even worse. Maybe it's time for a brown Maxima sighter! In these situations, I usually resort to watching the bow in the leader more for subtle twitches. Of course, it also helps to just set the hook now and then when you feel the drift is at its best.