That was certainly the view of many southern leaders in the mid 19th century. I wouldn't argue that.
It was also no doubt a real coloring of the view of some southern and perhaps a few northern Founding Fathers.
But I don't think most Founders would have understood the states in 1789 as "sovereign nations."
"But I don't think most Founders would have understood the states in 1789 as "sovereign nations."
You are incorrect. Every state constitution contained a clause providing for the re-assertion of that states sovereignity in the event of an over reaching federal government.
Until the mid 1800's the right of succession was never seriously questioned. Many states had threatened succession including New York and Masachussetts.
Even during the Civil War many people even in the north asserted that succession was constitutional. In fact this was one of the issues which moved Lincoln to shut down many northern newspapers and jail writers and editors.
It is true that several of the founders argued against succession in these early cases but only from the standpoint of what was best for the state - never was it argued that succession was on it's face illegal or unconstitutional.
If the founders had argued that succession was somehow illegal they would have been undermining their own assertions against England