The answer isn't to then set the $10,000 limit and add an opaque criteria of "but the limit doesn't matter if we look at your transactions and think you are hid

The answer isn't to then set the $10,000 limit and add an opaque criteria of "but the limit doesn't matter if we look at your transactions and think you are hiding something". Something more reasonable may be: a limit of $10,000 per month (or any time frame) before mandatory reporting. That of course means dropping the hand wavy exception completely.