None of those are debilitating issues. If the Confederacy is able to win a war against a Union that both outnumbers and outproduces them, then they self evidentially have enough social solidarity, gehmeinschaft, togetherness-feeling to make collective sacrifices to solve the problems of victory.
In this scenario, the Confederacy wins because they get lucky and miraculously roll all sixes in the Battle of Gettysburg.
Now, in an age where capability to absorb attrition and industrial capacity is becoming increasingly essential to win wars, they:
- Have a large area of their country ravaged by war.
- Have an industrial workforce/manpower limit of a literal quarter of the Union's.
- Have 33% to 40% of the population posing a constant internal threat of rebellion which cannot be removed without destroying their ideological "cornerstone".
- Large amounts of the rest of the population are economically marginalised and disenfranchised, with essentially no middle class,.
- Are reliant on a single cash crop for the vast majority of their economy, which is headed for a disastrous blight, and have no room to expand production.
- Have major hard limits on industrialisation because air conditioning won't be invented until the 1950s.
- Have a notoriously inefficient command-economy setup.
In a generation or two, the most likely scenario is the bluecoats coming back and crushing the CSA, and all "togetherness-feeling" will do is ensure a lot more of their soldiers get machine-gunned or artillery-shelled before they capitulate.
A confederate victory likely means Maximilian's Mexican Empire survives for starters.
It was already falling apart and only propped up with constant French support before the ACW ended. And it's not as if an America defeated in the ACW or a surviving CSA wouldn't have volunteers go over to join the rebels, and last of all Maximillian's empire was far from a reactionary project:
A provisional constitution was issued in 1865 ...
The emperor passed legislation guaranteeing equality before the law and freedom of speech, and laws meant to defend the rights of laborers, especially that of the Indians. Labor laws in Yucatán actually became harsher on workers after the fall of the Empire.
[24] A national system of free schools was also planned based on the German gymnasia and the emperor founded an academy of sciences and literature ...
Maximilian I wanted to reorganize the territory following scientific criteria, instead of following historical ties, traditional allegiances and the interests of local groups ....
intended to aid the development of the country by opening up the nation to immigration ...
Colonists were to be granted citizenship at once, and gained exemption from taxes for the first year, and an exemption from military services for five years ...
so IDK why you seem to view it surviving as a positive.
And if either Britain or France, or both support a Mormon insurgency in Deseret
Yes, they'll be able to transport guns and troops to the literal middle of the continent with ease. And Deseret was never intended by the Mormons to be an independent country, so there's no motive for them to start an insurgency that can be supported.
manifest destiny and the continental block ambitions of the upstart colonial republic could be contained,
If they're also able to magically sink California, yes.
Public opinion in both France and Britain, for different reasons, was that both had missed an opportunity to roll back World Revolution and Liberalism
They were far more concerned with the supply of cotton and trade goods from America than the grand ideological motives you seem to be projecting onto them. Plus the dominant ideology at the time in GB was classical liberalism, so you're at least half-wrong there.