So then all you have to do is funnel all your expenses through your business and not get a paycheck of greater than 20k per year.
You must be thick. The point of a 20% flat tax is that there is no way to do that. Income coming in to an entity is taxed at 20%. Doesn't matter if its a foreign entity (as long as the transaction involves an american) or shell corp or whatever, if it passed through your hands its taxed at 20%. In fact, using shell corps and foreign entities would become a bad thing as you would risk double taxation then. So routing all of your income directly to bank account would become the most tax efficient tactic. But it will never happen as tax attorneys, accountants, politicians and CEOs would all band together to stop it.