I'm sorry but although BBSs are cool, it's not really what we need. We'd like a forum that works well in regular modern browsers but also renders fine in Amiga browsers, like AmigaWorld or Amiga.org through the proxy.
If you were to use vbulletin, you're welcome to a copy of the proxy code. It is self-contained should be able to run from a subdomain without any issues. There are some limitations I never got around to fixing, one of which was file uploading.