Looks like I'm the only one still playing this game, haha.
I recently went for the Isle of Mann achievement (playing as Mann, conquer every island in the world, which is 408 provinces). If you just do a WC style run, it would be easy enough to get, but that seems too boring, so I self imposed a rule that I would not conquer any mainland unless it was for colonial nations. I actually used Maritime and Naval for the first time ever and they were my first and third idea. I didn't even use the old faith Administrative. I also didn't nation ruin England to start, just released and played as Mann for a little more challenging start.
It was a really interesting playthrough because it was pretty hard until it got real easy, heh. Starting out, paying for heavy ships is a huge burden and constantly taxes the economy. Furthermore, I went Pirate Republic and picked the reform that didn't allow any allies. So, the entire game I had no one but my colonial nations to help me. I didn't take any vassals because I knew they'd get swamped. As you get further along, you get enough heavies that you can defend all your provinces quite easily and then you do long blockades or some strike assaults on capitals with an expeditionary force. With naval superiority and only islands, the size of your opponent really doesn't matter at all. At one point, I was in three wars with Spain, France, a big Austria, Otto, a huge Tuscany and a bunch of minors -- and I purposely started them all. My land forces were outnumbered close to 10 to 1 but it just didn't matter because I killed or quarantined their boats and I slowly picked up the war score I needed to get the select few provinces I needed.
Definitely a fun run if you're looking to do something completely different, though waiting for war enthusiasm to tick down against a big alliance can be a bit boring when you don't quite have the navy to start another war.
Below is my bounty of captured flaghips (more were destroyed). I almost felt bad for Spain.... but not quite.
My boat totals at the end: