Bong your idea of writing the resignation in a way that explains the circumstances to any potential employer is indeed excellent advice.
It would also be advisable to show any potential employer a copy of the initial contact where the CEO was approached in a polite manner and given an opportunity to pay arrears. That way the employer can see that the candidate was not being militant, simply requiring payment for services. Any employer who has a problem with that attitude would be no good to work for anyway.