If one waits 72 minutes for melacha on motzoi Shabbos, is he permitted to recite Kiddush Levana prior to that time, assuming that no melacha (carrying) is involved? [Maybe someone else will carry the siddur for him]
Even though you wait 72 minutes not to do melacha, you may still say Kiddush Levana beforehand. The reason we don’t say Kiddush Levana on Shabbos is because we might come to dance, and according to some opinions because we may come to carry outside. However these concerns apply when it is still actually Shabbos, but not if it is already night but you still want to wait until a later time.
However if you wait 72 minutes for everything and until then your minhag is to consider it as if it is still not night for anything, then you should wait to say it.
One more point, it is always better to daven maariv before saying Kiddush levana because it is tadir.
M:B 426-12, Minchas Yitachak2-120, Daas Torah 426 -2, Sharei Teshuva 426-5, Chayei Adam 118-13