Joe,
How about question like-
Are / were you member of any other forum and what is your username?
Like former employment or former residency.
Then you can compare the notes with other B.Board owner, like validity of name claim and as a result, we don’t have to fear as much of undesirables.
Of course, we can have a –second chance- policy, but on –limited license- kind of probation.
After all we have proof that some rebellious members changed their behaviour, that you didn’t know what they did, you wouldn’t believe if somebody told you.