In December of 1860, at the South Carolina secession Convention, the Fire-Eater leader Rhett was opposed to including the Tariff as a cause of secession because the Tariff of 1857 was just as low as "the South" had wanted it to be.
The Buchanan administration entered office in March of1857 with a large amount of cash in the Treasury, a budget surplus, and a small government debt. The economy appeared rosy in 1856. The Southern-dominated Buchanan administration was opposed to the government having money, so they spent the cash and passed the Tariff of 1857 to lower rates.
This turned out to be very bad timing and misguided policy. The Panic of 1857 exploded immediately afterward.
The Panic had many causes (such as the end of the Crimean War, a surplus of shipping due to a boom of new construction because of the conversion to steam and the California Gold Rush, the sinking of the SS Central America with 30,000 pounds of gold, the popping of the railroad stock bubble, major flour and financial company bankruptcies, etc.) The economy of "the South", largely agricultural, was barely touched and generally prospered; the economy of "the North" (as in "the rest of the country") suffered badly. Southerners appeared to gloat over this.
In March of 1861, Abraham Lincoln arrived in office. The Treasury was empty. US debt had quadrupled. The budget was running at a huge deficit. Banks were demanding higher rates and special concessions to loan money to the government.
While there was certainly protectionism involved in the proposals for a new Tariff in 1860-61 (particularly on British iron and steel imports, which were killing the producers in Pennsylvania), there was also a crying need for more government revenue to balance the budget and pay down the debt. The Tariff and Federal land sales were the only real sources of income the government had.
"The South" was opposed to raising the Tariff and they wanted the cost of Federal land to remain low. I have never seen any proposal they made that would have generated money to deal with the government financial crisis they had presided over in 1857-61.