I’m led to wonder what if the Confederacy had pursued an all-out guerilla war instead of a conventional one. To emerge victorious, the South merely needed to continue to exist. It was the North that needed to conquer its enemy. A committed, armed Southern population fighting a guerilla campaign might not have been as easy to defeat as a Confederate army fighting full-scale battles (not to imply that four years and a half million+ casualties was “easy”, but you get my meaning.)
Guerilla warfare tends to be hard on your civilian population, witness the border war in eastern Kansas/western Missouri, so it's hard to see how if would have remained committed for long. And it's hard to say that you exist as a country without a government, without a capitol, and without an army.
The confederate guerrillas in Kansas and Missouri under Quantrill, Anderson and Clement were nothing if not well-armed and committed. In the end, though, they were hunted down and killed, even years after the war (when they turned into James Gang).