He shows that the vast majority of proposed amendments concerned slavery. A few were designed to provide a constitutional route to secession or to restructure the presidency as a multi-person executive. Only two proposed amendments had anything to do with tariffs.
If you want to understand what was on the country's mind a century and a half ago, those proposed amendments might be a good place to start. If you want to understand what Jefferson Davis thought, rather than speculate about his secret abolitionism, you might consider that the amendment that he wanted in order to save the union would have made slavery legal and protected in all the states.
That totally unnecessary because state secession is not unconstitutional, even now.