Thanks for the thoughts everyone. The original limited goal here is about breaking direct history of KYC coins (withdrawn from the CEX) on the public Bitcoin ledger.
In a world-wide crackdown situation I am not even sure a 5x mix coinjoin would be enough to stop a dedicated investigation given enough resources.
Is perfect the enemy of good? That said, a no-log alternative to FixedFloat and / or a self-custodial lightning wallet in the above situation would be even better than the original idea I proposed.
There is a lot of good info in @darthcoin guides.
This is why I put my coins in join market and leave them there for months. There's simply no way you could unwind dozens and dozens of coinjoins like that
May The Bitcoin Be With You!