I may be better at this game than I thought, because even with Venice landlocked, and me cut off from the majority of my trade routes for the first half of the game, by the time the nineteenth century rolled around, I was easily coasting towards victory. It's probably a weakness of the 4X genre that I subjectively perceive as a strength - once you start to pull ahead, you can use that advantage to pull farther ahead, until you're just an unstoppable juggernaut of rapidly-escalating power. It's probably for the best that I don't often play against other humans, because my favorite part of the game is likely the mathematically minimal amount of fun, when averaged over all the players as a group.
Which is to say - I won a game on King! I don't know what I was so afraid of. It was a little sketchier in the beginning, but once I got over the hump, it was just like Prince. I suspect the fact that I usually play to win a late-game victory probably factors into it. On hard mode, the AI gets an advantage starting out, but it is no more skilled at capitalizing upon that advantage than it is in easy mode, so if you know how to build your civilization, once you tip past the equilibrium point and pull ahead, it's literally the exact same game.
It gets me thinking that I should, perhaps, try an even harder difficulty level. I mean, a bigger starting advantage really just means the balance point gets pushed farther back, so it really shouldn't be too much harder, once you know the basics. However, even as I type those words, I can't help but see the hubris in them. I should probably go for it, just for the drama of my inevitable tragic downfall.