Frankly, if you're correct, it was a super top secret reason. Robert E. Lee didn't know it was about taxes, Abraham Lincoln didn't know it was about taxes, Jefferson Davis himself didn't know it was about taxes. We have tons (literally) of correspondence, speeches and declarations from them, and they all say the same thing. Ending slavery would be bad for the economy, so they rebelled.
That's the reason they gave, mixed in with some rhetoric about the Feds not having the right to outlaw slaves. It wasn't about taxes. You're just a historical revisionist.