“But in terms of the Constitution, the CSA was perhaps less evil than the North, wouldn’t you agree.”

I can’t answer for Anthony. But I certainly wouldn’t agree. Why in the world would anybody agree? The Confederate Constitution was deliberately modeled on the U.S. Constitution, and replicates nearly all of its defects. To these it adds new defects, in particular explicit new protections for “the right of property [sic] in negro slaves,” in particular explicitly forbidding any “impairment” of this so-called right by the confederate Congress (Art. I Sect. 9), explicitly protecting Confederate slaveholders’ ability to pass through or stay in other Confederate states with their slaves (Art. IV, Sect. 2), thus preventing any effective emancipation at the state level, and explicitly requiring that “the institution of negro slavery, as it now exists in the Confederate States, shall be recognized and protected be Congress and by the Territorial government” in all newly-acquired territories (Art. IV, Sect. 3). Alexander Stephens, famously, described the changes (which he regarded as an improvement) as putting “to rest, forever, all the agitating questions relating to our peculiar institution—African slavery as it exists amongst us—the proper status of the negro in our form of civilization.”

I can find no particular at all in which the Confederate Constitution is preferable, from a libertarian standpoint, to the existing United States constitution, with the possible exception of its ban on protective tariffs (Art. I, Sect. 8). But the Confederate constitution does allow for revenue tariffs and other taxes, and the Confederates at the time happily implemented every sort of tax, cartelizaton, and nationalization during the few years of their independence. In any case, compared to the massive and obvious evil of perpetuating chattel slavery, swapping on set of taxes for another set of taxes seems like pretty small potatoes.

So what exactly is a libertaran supposed to find “perhaps less evil” in the Confederate constitution?

“And in fact the CSA Constitution banned the slave trade”

Obviously it did not; they went on trading slaves. It did forbid the transnational slave trade (except with the slaveholding states that remained in the Union), which is something different.

Nor is it something especially noble. The prohibition on the transnational slave trade in 1808 was pushed through originally by the Virginian slavers. Not out of any moral scruple about trading slaves, which they continued to do with gusto, but rather because certain powerful slavers profited greatly from the internal slave trade, even while plantation agriculture became increasingly unprofitable for the longer-settled parts of the South. The basic impetus behind both the 1808 ban and the Confederate ban was not emancipatory; it was just another damn protectionist scheme.