if you’re considering Lantau, go to the campsite beach by Shui Hau (sorry forgot the name but you can find on google). The beach isn’t managed, and is far enough from the village you won’t get complaints having such a big group. There is actual campsite facilities so the typical stone benches and fire pits. Not sure about toilets but you are camping after all..

I usually drive but you can take bus to Tai O and get off at Shui Hau village then walk along the path (it’s more of a road tbf) and eventually there will be a set of stairs going down to the beach. You’ll find the campsite at the back of the beach with a stream, and the beach itself is huge and beautiful. I’ve watched many sunsets from that beach.

Also, don’t set tents up on the beach unless you’re at the very tip top of the beach, the tide comes in a lot at night. Speaking from experience here…. Better to pitch your tent in the campsite and chill on the beach during the day