I agree sign something with B8gZqgY4r2RoEdqYk3QsAqFckyf9pRHN6i
Millions of people have this as the example address in their wallets. (blackcoin and all blackcoin forks.) so millions of people already know that rat4 wallet address is B8gZqgY4r2RoEdqYk3QsAqFckyf9pRHN6i
And we can all verify the signature with the blackcoin wallet by clicking File->Verify message.

(I don't exactly know if there are really millions of people, I just guess.)