Hoppe prefers a private-law society to even monarchy (and I agree with him).

I do think a propertarian monarchy is an improvement over a divine-right monarchy, and a divine right monarchy is a (marginal) improvement over democracy (for the reasons Hoppe argues).

Why does the king get to charge you to use the port? In a propertarian monarchy, he owns the port. No special rights or deviation from the rule of law is needed. However, if the king has the right to suppress the construction of alternate ports (on others' land), or to demand that you not offload goods to small boats to avoid the use of any port, this is outside the bounds of what property can accomplish.

In a divine right monarchy, the crown is free to abuse the rights of the people. The king charges you to use the port because he has the power to do so, and the blessing of God over all his actions. He can and will forbid alternatives. Perhaps he gives the blessing of "monopoly" to favored associates.

I repeat my recommendation to you of HSH Hans-Adam's "The State in the Third Millenium". Modern states are undergoing a crisis of legitimation, in which divine blessing is no longer seen as sufficient to justify the power of the political elite. The stopgap has been democracy, but increasingly it is only a tenuous theoretical link (as in Washington & Brussels). The suggested alternative is genuine consent and the transformation of modern states into peaceful service companies (eg with guarantees of a local right of secession, as Hans-Adam promoted in Liechtenstein).