Is there a rule of thumb for the size of pendants in relation to the size of a kitchen island? My island is 88" long and 36" wide. I understand that you should have the lights at least 18" in from each end of the island, but what about the size of the dome itself?? I am looking at 3 pendants that are 6.75" wide and 7.5" tall. This pic is the "before" pic of course. Changing the fixtures.