I don't really make use of the sunset time directly, but I have a tile on my dashboard with the sunset time showing, so I can actually see what time the lights should be turning on if I have used this in RM. The most important (and probably most difficult) is the LUX reading. I know this is not accurate but it does give me some sort of "brightness" indication. I am looking at getting a lux sensor in the future, but at the moment I use Dark Sky for this reading to get lights to turn on even before Sunset if it is dark enough
Thanks for the effort you are putting in. .