Carlist vicoty is useless too. Spain's government can simply choose the ruling party, so you place the Carlists on top by Royal decree, and now you can build factories to your heart's content.
I have yet to try it myself, but my understanding from the corresponding thread at Paradoxplaza is that letting the Carlist rebels win creates a government with "Ruling Party Only" in the Upper House. This means that reforms can be made (except to the UH) at the player's leisure. Just appoint Liberals for Political Reforms, etc...
Anyway, here is how my Prussia/Germany game finished. Rebels broke A-H. From what I gather there were both Austrian Nationalists and Anarcho-liberals. Austrian Nationalists occupied some provinces, and released Austria. Everyday, the new Austria triggers the Austro-Hungarian compromise event and creates A-H, trading places with the previous A-H...
Screwy. I couldn't get it to quit, so I installed 1.3 and moved on to a CSA game.
My CSA game at halfway.
Civil war hit late 1861. I had the usual cores + the plains states, Wisconsin, Colorado, Wyoming, Montana, UT-Nevada, Idaho, Oregon, Chihuahua, St. Thomas (place in the Sun CB vs. Denmark in 1840s). Another year or two I probably would have had Washington and Michigan as well.
Took Missouri and Sonora in the 2nd war (Sonora and Chihuahua both conquered when I was still USA naturally). France intervened in that, I think because my ally Peru claimed land from Colombia w/whom they were Friendly. They didn't land any major armies though, and I took Martinique off of them.
The third war was huge. USA fielded a larger army than either time prior, and the tech was getting to the point that it favors defensive warfare.. I was just hoping to take my WV cores, as my infamy wasn't entirely worked down from my previous grabs. Nevertheless as it escalated and I worked them down, I decided to weaken them more adding MD, PA (10 infamy) and freed New England in MA (3 inf.)
The fourth war came soon after thanks to a lucky event giving me an Add State CB. I used it to take California for free. UK declared on the USA at this time also, so I gave New England the rest of their cores (3 more inf) to keep the UK out of there.
Infamy is still under the limit ~20-21. Britain is still +200 with me - not ready to go after them yet. Colombia, Brazil, Peru, Ecuador, Honduras, Hawaii, New England all sphered. Mexico is "Friendly." I also own the Panama Canal.