Personally I would keep on checks like NastyHosts and keep the minority of real people that are blacklisted wouldn't be able to access the faucet. I cannot imagine there being a safe way to prove that you are an owner of a real IP for whitelisting, and not just a bot owner asking for his bot to be unblocked.
However, I am not a faucet owner and I'm only speaking from what I have read and my own judgement. You would be better perhaps asking other owners of major faucets how they keep away bots and such.

Thank you for being understanding.