@Michael Pyle , perhaps I am wrong, but I would be willing to bet that the majority of posters on this site are a good 30 + years older than the crew in your photo. The average "Waynes Wordling" will have a very different perspective of how to enjoy the lake than you will.
Unlike others, I don't think you can compare Lake Powell to a campground anywhere. If you have people camping so close to you that your ropes are touching, you are not going far enough from the Marinas.
I long ago lost count of how many trips I have been to Powell. In all those trips, the only times I can think of when loud music at night was a problem are the times we actually stay in the slips. I can assure you, if there really is a 10 PM quiet hour rule at the lake, it is NOT enforced.
My advice to you is to do as has already been suggested - spend a little more time finding the "right" campsite. To me, that is one that is protected from the wind and wakes, and is remote enough that unless you are REALLY booming your music, it won't bother anyone. I was at the lake for the last 10 days, and the closest houseboat to us was about 6000' away.
And for the record, our group was in bed every night by 11 pm. And I'm not a fan of loud music (or loud exhaust on boats). But I am a fan of being responsible, and letting people enjoy the lake however they like, wether that means getting up at 4 am to go fishing or staying up until 4 am doing your thing.