Are there any surviving documents from the Confederate leadership discussing what they would have done with the northern states if the south had won the Civil War? I'm curious if they planned a military occupation or if they would have enforced a border between the north and south and avoided trying to exert influence in the north.
The Confederacy had neither the will nor the resources to occupy the Northern states. The Confederate vision of victory was either a) win intervention from European powers in the conflict to force a Northern defeat or b) get Confederate sympathizing Peace Democrats in the North to defeat anti-slavery or outright abolitionist Republicans in elections and negotiate a peace. Richmond was very hopeful this might happen in 1864, and even had a limited stream of funds to aid Democrats in the North. Confederate spies also infiltrated the North via Canada to try and undermine the Union war effort. Lincoln and the Republicans triumphed under the National Union ticket anyway however.
The Confederate vision of victory was peace with Washington and recognition of CSA independence, as well as opportunity to expand the slave economy into the Western territories (the major reason why they seceded upon the election of Lincoln). Apart from maybe a handful of rabidly pro slavery Fire Eaters, the Confederates had no plans to annex northern free states. They did try to annex Union slave states that didn't secede during the war however.