While we are in the same discussion of a southern Illinois secession. I think it would have to be a northwest conspiracy turned rebellion .
Suppose of all went well in 1862 for the confederacy under different leadership
suppose of Shiloh was a Confederate victory because
Beauregard was ordered to defend New Orleans.
And what if the historical confederate victories where more meaningful such as larger armies destroyed thanks to lee having to all of Jackson’s advice
Yes it’s possible!
1862 border state invasion(Kentucky, Maryland,Had pea Ridge been successful Missouri too) confederates almost took Kentucky that is true . Frankfurt Kentucky is not far away from Louisville . Brag they most incompetent confederate general instead of continuing to block Buell from getting to Kentucky it asking for Smith to come as reinforcements because a battle looked possibly.
Brag withdrew And didn’t even run away to didn’t even run

to Louisville where the Yankees needed to Re-supply there depleted stores .
In Maryland Had Confederates stayed in Frederick they could have won instead of being defeated at sharpsburg Antietam . I’m saying this because of geography. The union would’ve been defeated but it would not have been catastrophic and they could easily retreat back to Pennsylvania. Confederate forces could’ve already Marched on Annapolis and possibly even before Frederick.
Especially if they had more meaningful victories but it’s also true that only elements of the army of the Potomac were in Frederick ay
i’m curious to when Lincoln would sign The emancipation proclamation? making a northwest rebellion possible in 1863 but most likely 1864.
i’m not sure about the long run for Kentucky how long will be able to hold it but in the short term it’s at least good.
Horses,railroads, essential supplies in Louisville,
Possible striking distance for raids possible striking distance for raids and sending weapons to copperheads in case they rebel.
Use Kentucky as a buffer zone .