The OP is gone-- but this article may be of interest:
http://www.skyscript.co.uk/triplicities.html
Houlding says that the Hellenistic astrologers gave 3 triplicity rulers each, for day and night charts. The moon does show up as one of the triplicity rulers of the water signs in this scheme.
Further, she notes that some of the ruler assignments were not based on an affinity between planets and elements or day/night, but rather to moderate the excessive effects of the malefics. Hot dry Mars is moderated at night, just as cold Saturn is moderated during the sunlight hours.
Presumably, if you're going to have Mars somewhere in a chart, it's better to have him in a sign like Pisces that dampens his excessive heat and dryness.