The smarter move if this was 1 person who intends to use the 4+m to live off, and not buy a Lamborghini or some stupid shit, would be to extend the timeline much further past 1100 days. The smaller the individual amounts the better. If they are long term bullish on the prospects of bitcoin retaining its value or increasing, launder just enough to pay themselves a nice monthly 'salary' for living expenses, under 200k a year, and take a lot of time to consider what to do with the rest.

And dividing it up between as many possible independently run tumblers/mixers.

I'm sure some additional smurfing techniques could come into play for additional obfuscation.