There wouldn't need to be.
The Supremacy Clause says that all state laws are subject to Federal review.
An "act of secession" is a declaration that no laws of the seceding state are subject to Federal review, which is a direct violation of the Supremacy Clause.
No, that's not quite right.
Yes, there is a Supremacy Clause - but only for valid federal laws. Meaning laws “made in pursuance” of this Constitution.
That includes amendment IX and X. And Article IV, Section 2 if you must have it.
You ignore the phrase “made in pursuance thereof”; you and I both know why. In that way you can ignore the concepts of dual sovereignty and powers not delegated.
However, you have one argument that is persuasive: the toeboard clause of the federal Constitution. You'll find it right next to right-to-abortion clause and the men-marrying-men clause in the Constitution.
"1910.23(e)(4)A standard toeboard shall be 4 inches nominal in vertical height from its top edge to the level of the floor, platform, runway, or ramp. It shall be securely fastened in place and with not more than 1/4-inch clearance above floor level. It may be made of any substantial material either solid or with openings not over 1 inch in greatest dimension."
Without the toeboard clause, rebellious states could adopt toeboards with 3/16th clearance above floor level. Or no mandatory toeboards at all. And that would be disasterous. Right?