I've been to the wrecks a few times and with a tribe of kids(8-15yrs) and adults and we loved it. If your real sneaky like we are, we had hot showers at tangalooma where they hire out the wind surfer stuff as they had showers in there at the back. There were only compost toilets and cold showers at the camp site when i was last there some years ago. But as for things to do with teens i think the wrecks are great as you have sand boarding, snorkling the wrecks and close to tangalooma. Plus if your sneeky again just go on the beach at tangalooma around the 5ish mark and just look like your a guest there and then you have night entertainment at tangalooma when you come back off the beach. They usually tell campers to go home at around 5pm but if your not yahoo's they generally dont mind lol.
I know i'm a naughty girl and only paid $3.50/night at the camp site instead of $350/night at tangalooma and got to use all of tangalooma's facilities
but it works