Well, I've tried the idea and it does indeed work:
I ended up needing just 1 Great General, by applying the advice and follow up idea by
@Zalfos , especially the part of not getting ballistics so as to not obsolete the musketeer. Got it attached to a stack of 20 8XP units and it worked, for the other 10 I got 3 fighting aboriginals, and the other 7 fighting Indonesia.
There's probably some more optimization needed, as the whole point of doing it with just 1 GG was so that I could stay with Constitution, then do 1 civic switch to Totalitarianism + Fanaticism, 1 more to go Stratocracy + Secularism when I was ready to upgrade, and a final one to go back to Constitution + Individualism (or Egalitarianism). The problem was that by the time I did that, I went over the limit of cities and those 2 final civic swaps cost 2 turns of anarchy each, so I ended up not switching out of Stratocracy and Totalitarianism, as I didn't think it was worth the 2 turns of anarchy
I don't remember what was the city threshold that made you increase the anarchy turns, does anyone know?
I did settle a few more cities after the initial UHV and conquered one from Java:
- Hobart, to get the whale in Tasmania in my borders.
- Cairns, to get the jungles in my border for nature reserves.
- 2 Polynesian islands for the pearls
- Wewak in New Guinea, just for the heck of it
- Conquered the 2 easternmost cities in Java, Trowuland and Denpasar and capped Indonesia since I had enough 9XP units, gave back Trowuland but kept Denpasar for access to the whale and pearl
Of these, I could maybe avoid settling Hobart until later, if you keep Denpasar, you only need 1 of the Polynesian islands for marine reserves and Wewak is unnecessary, so that would be 3 fewer cities, putting me at 15. Don't know if I go over the cap with that.
In general, I think it is a fun civ to play with a bit of everything. The only thing is that the unique units are not useful at all, with the digger even being detrimental due to increased cost of production compared to a musketeer, and the fact that it obsoletes any lvl4 musketeer you got for the 2nd UHV. The unique power is amazing and synergizes well with the 1st and 3rd UHV, and the unique building is a bit meh, the ability to build it comes a bit too late (you need to build observatory, factory and coal plant first, while having to do many other things in the meantime), and that free scientist doesn't make that much of a difference for the final push in tech in the short timeframe you are going to have it.
For unique unit it would maybe have been more useful to have maybe some sort of transport with extra movement, a worker with extra movement, improvement speed or even mobility, or a worker you can draft like a military unit with Nationhood.
For unique building it would be more useful perhaps if the CSIRO replaced the observatory instead of the laboratory.
Anyway, fun civ, fun UHV and great addition overall!