I agree with Randy and KB. Your FI is not this customer's de facto regulator. I'm not even sure how you would monitor whether a dealer is filing form 8300 accurately? Think about it. Are you doing this for attorneys? Or other professionals who could receive a payment in excess of $10,000?
I would stick to filing CTRs and if appropriate, SARs on this customer.
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"100 victories in 100 battles isnt the most skillful. Subduing the other's military w/o battle is the most skillful." Sun-Tzu