Thanks a lot for the elaborate reply!
As it is right now, England has "they want your provinces" unfortunately, which gives an insurmountable negative relation with them, so it's going to be tough allying with a big navy nation. France has been almost wiped out of existence, hah. This playthrough looks like blob-land all around.
On my last session I actually had a very good chance when I supported Portuguese Mexico Independence (and they had a very big navy and army), and I even got to capture both Galapagos and St Helena, but not enough war score to get them for myself in peace negotiations. Very frustrating! And right after we won, Mexico got "want your provinces" penalty also, so I couldn't even enjoy the new strong ally.
Sadly, I think I might be running out of time. It's already around 1783, so less than 40 years left, and my last ditch strategy is to pour thousands of gold into navy buildings to raise my navy force limit and build a huge fleet to try and be able to stand up for myself, but I'm honestly not very confident it will be enough. My force limit right now is around 90, Spain is like 400... I might have a failure in my hands up until the end.
But I'll definitely try to work some way into finding a strong ally and luring them in. As for your last advice (the colonial province claim idea), I'm not sure if it applies because those islands are actually a part of their realm, and not the colony name they usually have such as 'Portuguese Mexico', it actually says Portugal.
Tough times ahead, pray for the sun gods guys. 20+ hours and the goal is not looking very likely.
Yeah, France might not be too useful in that game!
The lack of claims is a bit annoying, I'm not 100% sure how that feature is supposed to work. Are there any vassals you can release who have claims on any of the islands? If so (and it's a reasonably small vassal) you should have enough time to release the vassal, use its claims to declare war, occupy the islands, avoid other fights wherever possible, and simply wait for ticking war score until you can claim all three (they shouldn't be much war score each). Then, 10 years after the vassal has been released you can integrate it again (which may take a few years depending on the size of the vassal).
Regarding naval limits, keep in mind that heavies are far stronger than any other ships, so if you can afford it, then the ideal composition is enough transports to take the islands and then all heavies for the remainder. Hell, if you can afford to go over the naval cap you might as well, as it's not
that expensive. Again, keep in mind their number of transports, and compose land regiments that are big enough to take out the largest possible landing party (two or three for the mainland, and then ideally one each for the islands). If, let's say they have 30 transports, and you set St. Helena as the war goal, then if you drop a well-designed 50 stack on St Helena (30 infantry/cav, 20 cannons), and are at relatively equal tech, then it will be effectively impossible for them to retake the island, given your numerical advantage and the -2 penalty they'll get from landing from sea. You'll likely take some attrition on St Helena (it's unlikely they'll have developed it enough for a 50 land force limit, although if you have a leader with high manoeuvre it'll help), but you get a guaranteed ticking warscore, plus bonus warscore every time they try to retake the island. So long as the rest of the war is pretty even, that's probably enough for all three islands in one war.
Plus, if you do it while they're engaged in another war in Europe, they may not even bother fighting you over the islands (particularly true if they're losing their European war). Attacking while they're in another war also decreases the chances of their allies joining, which should make things a bit easier.
That's true of many paradox games. The majority of games last something like 100-150 years. Pick a goal that looks fun and go for it. Once done, see if anything else looks like fun. If not, start over and try something else.
Particularly so for CK2, with the expansions you can now play for almost 600 years, whereas I feel CK2 works best on smaller timescales, given the focus on individual characters. Some people just play a single character until he dies, or you can go the "quantum leap" route and just randomly pick a new character each time your one dies (within the same saved game).
Paradox's achievements also tend to work pretty well if you're looking for a goal to work towards. They even have a reasonable number which can be completed in relatively short timescales (and some, in EU4 in particular, which
have to be completed in a short timescale).