Society has already made a judgement that those overtime hours only make society better off when an employer is willing to pay extra for them. Implicit in that is a judgment that neither employers nor employees properly account for the social cost of that overtime (because of short-run vs. long-run considerations, impacts on third parties like the employee's friends and family and so on).
Making the case that the social costs have changed and revisiting that judgment democratically is one thing. Evading that judgment by trickery (especially when that can involve tricking the employee) is something very different - cheating the system by shifting the social costs of overtime where they do not belong.