vbStopForumSpam is a good way to keep a lot of them out to begin with. One of my sites gets a TON of attempts a day that are blocked by it.
As far as not showing up on the member list, I suggest the following setting in the AdminCP.
User Listing Options => Minimum Posts = 1
This will at least keep them out of the member list until they can post a message.
They will still show up in teh "Welcome to our newest member," section, but then there will only be the latest registered member.
I also blocked viewing of the member list to registered, logged in members only.
vBStopForumSpam link
https://vborg.vbsupport.ru/showthread.php?t=230921