Tu quoque is also a fallacy.
First, how do you calculate that three quarters of tariffs were paid by Southerners when no such stats exist. I know its intertwined with exports and specie and things like this but if you clarify your reasoning then I can avoid critiquing an argument yourre not making. Thats fair of me, dont you agree?
Second, how much would you estimate that investment in new warehouses, ships and trains, as well as continuous operating costs of the same, plus additional insurance, unremembursed losses, commissions, etc. that Northerners carried before 1861 would cut into that 40% off the gross that Southern financial interests hoped to reap from cutting out the middleman?