“The tariff amounts paid by the south were not exorbitant. In fact the amount of tariff paid in southern ports was a small fraction of the amount paid in northern ports.”
You have it exactly backwards.
The industrial north wasn’t importing manufactured goods, they were producing them. Their industries were protected from lower priced European competition by the tariff. Their wages and profits benefited from the tariff.
The agricultural south purchased its manufactured goods from outside the south. The tariff raised the cost to them of imported European manufactures, or if they bought from the north required them to pay the higher prices that northern industries could command due to the protection rendered by the tariff.
Go try to sell your tariff theory to some libertarians, they’ll give you a lesson in how tariffs work.
Lesson not needed. The southern slaves were not much into luxury goods, or much into the manufactured products that were converted from imported raw materials.
The smaller southern population, and the even smaller share of people who consumed manufactured products at a high rate means that tariffs were paid mostly by the people of the north.