You provide a bunch of great resources--but I think you and Remarkl are not talking about the same thing.

Your links demonstrate very clearly that slavery was immensely profitable to the South. But that isn't enough to demonstrate that "there would be no America without slavery".

Indeed, your own links show that slavery in the South was only keeping pace, economically, with industrialization in the North--and only per capita, not overall (the North had the larger population). After all, the South lost the Civil War, which would be peculiar if it was the dominant economic power. (It was not; and the overwhelming majority of slave labor was in the South.)

If you want to wrap up the argument in your favor, you have to additionally show that this extra economic output made the critical, irreplaceable difference between America being an independent entity and not. So far, all you've shown is that it was very important, and as far as I can tell Remarkl didn't actually dispute that.

One possible approach would be to make a strong argument that without the economic power of the South at the time of the Revolutionary War (specifically, that part due to slave labor) that the war could not have been successful. Other approaches might also work.