I checked out your blog post on this. The sign won't help. If somebody wants to play dumb (sometimes not playing) they'll just say they didn't see the sign. I agree with one of the commenters on your blog - drinking and noise go hand in hand.
I worked at a campground in the Ocala National Forest one season. Apparently it had a reputation as a party campground cuz we had all sorts of trouble every week. On the brighter side, the local sheriff was very quick to respond when we called. When a camper gets cuffed and tossed in the back of a cruiser, the rest of the campground tends to get very quiet. :-)