>>4036
If there are public proxies such as Tor, their IPs should be publicly available, so they can be blocked. If I'm not mistaken, the current board software hashes CP images and prevents them from being uploaded in the future. But unfortunately changing even a pixel can get around that. In the BO panel, you can block Tor users from posting images. That's a big deal. You can still let them post text.
Otherwise, I can only recommend more comprehensive moderation. Get some volunteers for each timezone and make sure to pay attention to the report feature.
It's also possible to block by ISP or geographical range. But you have to get the site owners to do that.