unity – Circular Z ordering problem

I am creating a day-night cycle for my 2D side scrolling game and I have a big problem. The problem can be best understood if you look at the following image:

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Problem is very simple: the moon should always be behind terrain (otherwise it would look weird) and terrain should always be behind a light-map (in order for light-map to draw shadows over the terrain).

However, the moon should also appear in front of the light-map, since at night it shouldn’t be affected by the light-map darkness over the terrain (light-map should only apply to the terrain).

Essentially, I have the following situation: A should be behind B, B behind C and C behind A (circular ordering). Is there a trick to solve this problem?