I'll certainly open source the code! I just want the flexibility to change my rate limiting logic in the short term to counteract abuse. Happy to answer questions though!
It's kind of annoying and expensive to get a bunch of IPv4s to evade limits, but it's really easy to get a TON of IPv6s.
The other Big Trick I know is to persist rate limits after a client disconnects so that they can't disconnect -> reconnect to refresh their limits.