I could probably find an address you don't want to just block once I know your firstandlast.com domain. Why not use @fastmail.com (or any of Fastmail's other domains) for throwaway aliases?
I don’t doubt that you could, but in my experience spammers are invested enough in a single individual to get clever. We’ll see. I enjoy having a predictably unique login for each site {site@firstandlast.com}.