Re: Handling day and night on infinite plane?
How about some sort of "shadow" substance between the infinite plane and the eternal light bulb. It would operate similar to the shadows one sees in clear shallow water. The shadows, or night, would be where the waves are rising and falling. There would be two "days", one where you are at the crest of the wave, and one where you are at the dip of the wave.
So imagine the atmosphere as being the water... When you are in the "dip" of the waves, the atmosphere is at it's thinest, so it would appear to one standing at the bottom of the air that they are at High-day, because the light passes through, and it's thin, so your goody-two-shoes-aligned gods and spirits would be at an advantage. Then, as the wave starts to rise, it would block the sun, and you would have night. As the wave crests, you again have a "day" but it would be a different day, perhaps leaning toward some other type of gods. (if you want to keep night time for skeletons and devils, use some other identifier, perhaps the new gods vs nature and elemental gods.) The wave crests would be called "low-day" to an observer on the ground, due to the wave being thickest, and blocking out more of the good stuff. Whatever that is. As the wave drops again, night approaches and it starts all over.
I've had a few beers and there's noone to talk to here, so hopefully this helps someone.