I agree 100%, that's what you firmly believe.
But, it's not what our Founders said, ever.
What they said instead had everything to do with "a long train of abuses and usurpations", and nothing whatever to do with an alleged unlimited "right of secession" at pleasure.
Indeed, the whole idea of secession at pleasure was anathema to them, as clearly spelled out by the Father of the Constitution, Pres. James Madison:
You keep bringing that up as if it is significant. Yes, they wrote what they regarded as justifications for what they did, but they made it clear that they didn't have to justify their independence, they had a right to it whether the British liked it or not.
"...a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation."
... is a courtesy, not a requirement.
Indeed, the whole idea of secession at pleasure was anathema to them, as clearly spelled out by the Father of the Constitution, Pres. James Madison:
I am well aware that the only evidence you have in support of your position is two letters from James Madison, one written 40 years after the constitution.
The problem with this evidence is James Madison contradicts the very words he and his committee created in the Virginia ratification statement in which they make it very clear Virginia has a right to take back its powers.
In the case of the Virginia Ratification statement, Madison's is not the only voice put forth. It was the entire body of the representatives of Virginia that issued that statement, and therefore it is of greater authority in determining how they understood the relationship between themselves and the Federal government.
If Madison contradicts them, so much the worse for the reputation of Madison.