Don't know about trout fishing under a full moon, but it can make it tougher in bass fishing, because the fish will feed all night, then maybe not much in the daytime...but that is in heat of the summer, and all the noise from the morons (waterskiiers and jet skiiers) might have something to do with it. I have heard the full moon phase can make the Sierra lakes tougher in the summer, but I wouldn't worry about it now. Besides, you are going to the Sierras, it can't be all bad!!