Navigating AML flags for offshore entity funding

Been thinking through the challenges associated with clients funding trading accounts from offshore entities, particularly those in jurisdictions with less robust transparency. What's everyone's approach to AML red flags when the source of funds is a multi-layered corporate structure in, say, BVI or Panama? The KYC for the ultimate beneficial owner (UBO) is one thing, but establishing the legitimate economic purpose for the transfer from that entity, especially when it's not a primary operating company, often feels like chasing shadows. Are you relying heavily on bank attestations, or are there specific documentation requirements you've found effective in mitigating that specific risk?