Although moonlight is used most often as a noun ("the light of the moon"), it is also an adjective (a moonlight evening) and a verb ("to work at a spare-time job"). When used as a verb, moonlight forms its principal parts as does light: moonlight, moonlighted or moonlit, moonlighted or moonlit. Thus it is correct to say "He moonlighted for extra money"; "It was a moonlighted (or moonlit) night"; "The evening was moonlighted (or moonlit)." Moonlit is the preferred form of both adjective and past participle. Moonlighted is the preferred past tense of the verb. See also lighted.
Dictionary of problem words and expressions. Harry Shaw. 1975.