In reply to iksander:
I've got several wild camping spots in the Brecons, and the reason that they are my favourites is because they are truly wild, and the reason that they are wild is because I don't publicise their locations!
Sorry, I'm not being deliberately unhelpful, but so far as any wild camping goes I believe that's the way it should be.
However as a hint I strongly recommend that you pore over a map and using that find your own potential spots - that's the fun and magic of a wild camping backpacking holiday.
That's exactly what I did many years ago with my teenage son and we had a great time. Do involve your daughter in the planning, if she's like my son was, she will appreciate being involved to that extent.
Good luck and happy camping!
Post edited at 17:39