Well, I would've resigned too.
Your last turn before the resignation, you could've just bought 3 pawns to end the game.
In fact, once you'd emptied the peddlers, I would've just spent your turns buying native villages and pawns - you could've been done by turn 14.
Pirate Ship was going to be a losing proposition on that board - there's just too much non-treasure cash about, and even if he hit all your copper, that's only $7 ships with an $11 target, so there was much you could do to screw that up.
I'm not sure, but I've got a feeling that using expand+peddlers might've let you plough through the colonies even faster than three-piling, but with your opponent emptying out the native villages, three-piling was definitely the way you should be ending this one.