Taggart 
It was my job for a decade to try to keep tweens and teens safe online. Let me tell you what you already know: no law or technology can do it. There are no lengths kids won't go to to talk to friends without prying eyes. The harder you try to lock it down, the dodgier their solutions will be.
HardlyWorgen@mttaggart My brother tackled online safety for his kids by not allowing them to have their own computers until partway through high school. There was only one PC in the house, and it was in the parents' bedroom. At some point the kids got laptops so they could type up school papers, but my brother would shut off the wifi to limit the kids internet time.