Taking out Spain and the Ottomans is going to be toughest part. I did this same run quite a while back before absolutism, and I finished it in 1780 at a leisurely pace. This was my strategy.
-Ally Castile and spend the entire game fishing for a PU
-Take the Irish province instead of a core after your first war with England, Diplo vassalize an Irish Minor(I picked Leinster to keep the British from doing the same) and use them to eat all of Ireland.
-Declare on Aragon(Promise Castile Land) and release Naples, take a province in Naples or an Island that is in range to fabricate claims(I got lucky and got the event giving me free claims to all of Naples). You're going to want to release Naples for a few reasons, but mostly to keep Castile from acquiring them in case the PU falls through.
-Now the Truce with England should be up, and if you fed Castile you have plenty of Favors. Declare a Reconquest war against England. Castile will handle the Mainland while you stomp the British. Take back your cores and a firm foothold in England. Eat them at your leisure. I allowed them to live so they would colonize, then spent the whole game stealing their colonies.
-Finish the Job on Naples. It's fairly high AE, so you might need two wars. Fight Burgundy at some point and try to force the event that gives you their land for free. If it wont pop, take land you wont get in the event.
-Now the tough part, time to go after the Ottomans. You want to crush them before they get overwhelmingly large. I allied Hungary, vassalized Serbia(Mostly for a staging ground), and I hard rushed Forts with defensive territory. After a bitter war of attrition I was able to get enough warscore and rack up enough war exhaustion that the Ottomans gave me a nice bit of land. I Isolated a province on the coast and took Mountain provinces all around it. I built Forts on the Mountain Provinces, and made the Isolated province the War goal in the next war. This makes for a super easy meat grinder even if they have double your force limit(They took Quantity in my game). The next war take a Byzantine core, release them. The next war declare for a core(I declared for the southern most tip of Greece. It has a fort and it will be easy to isolate.I declared for this province in every war until I could manhandle the Ottomans without effort). I made Byzantium a March and sent officers. Slowly but surely I pushed the Ottomans further and further back until the only Province they had in Europe was the Fort I was cheezing them with. With their high development provinces gone, their excellent trade node gone, and their oversized military draining their economy they become a pushover. I hit this point at about 1595-1600.
-Take Exploration with your 4th Idea(Diplo-Defensive-Admin were my first three) and start stealing Colonies from Portugal and England, colonizing where you like. I colonized Africa and stole colonies in the new world. You're more likely to have rebels in the provinces you take by force, and in the new world your CNs will take care of the rebels. This make for less of a headache shipping troops around. You can take Humanist later to avoid this altogether.
The rest is just playing the game, and taking what you need. If you're lucky(I wasn't) you can get Spain in a PU. If not it's no big deal. I'd give it a shot until you have max absolutism, then break alliance and take them over in a few wars. Make sure to get the islands that count as Spain. Italy is also pretty easy to pick off bit by bit. You get free claims on Milan and Savoy. Venice is easy pickings. Just don't get greedy and take too much AE, and wait until last moment before taking Rome. Cripple Austria when you see an opportunity, no need to rush it.
I had a little luck in my game. I managed to force a PU over Hungary, I got the BI after taking land I wasn't going to get. I got the Naples event. My first war against Spain, they were in the middle of a crisis and had just lost a CN. That said, I also took my time, never ran out of manpower, and almost never used mercenaries. Outside of the first two wars with the Ottomans I never broke a sweat. I also got Better than Napoleon.
Best of luck, sorry this was so long, hope some of it helps.
But I assure you from reading a good part of his posts that he usually knows what he's talking about; he just assumes a player can't get outmicroed by an AI which is unfortunately wrong.