How will Usal Beach be during the week in mid June? What do you mean when you say a $h** show? How bad are we talking about?
The locals have been partying at Usal for years, and when they party, they party hard. For Holiday weekends like the 4th and Labor Day, you may encounter 100+ vehicles camping on Usal Beach (it's illegal to drive on the beach, please respect this). Expect loud music, people partying past midnight, folks doing donuts on the beach and through the campground-- sometimes folks are firing off fireworks (another bad idea, the burn zone on the way into Usal was started by a firework a few years ago).
It can still get rowdy on weekends, but if you camp back further into the redwoods near hotel gulch, things are generally quieter back there. All of the madness seems to happen on the beach and the sites closer to the beach.