How did the framers of the Constitution, like James Madison, go “beyond Montesquieu?”
The original question had to be edited down. I would suggest that one way in which the framers of the Constitution went "beyond" Montesquieu was that they strove to construct political reality. Montesquieu's theories were simply theoretical exercises. Montesquieu, himself, never conceived of them being reflected in practice or in a realistic political state.
The framers took Montesquieu's political theories of divided government, separation of powers, and branches of government and applied them to the realistic condition of the young United States. The framers understood the real problems of the dangers in centralized government and sought to find a solution to them. They understood that the Articles of Confederation were not working.
Using political theory to authenticate a working experiment of government became the framers' mission. They moved beyond anything that Montesquieu could imagine as they applied his political theories to the reality of America. In this, they saw that political theory could be useful in practice, something that Montesquieu himself did not imagine. It is in this way that the framers of the Constitution went beyond theorist Montesquieu.