Independants dont like AI's...

[Arralen]

Or 'better' yet: Set up nations as player nations and hand them over to the AI.
O.c. that lets you know everything about them, but at least they don't shoot themselves in the knee by choosing a sense-less setup. (I'm not sure if the command-line argument for setting AI strength will work in that case. I'm pretty sure it did for Dom2, though).

[HoneyBadger]

You can take like a piece of cardboard and cover the screen that would tell you where your enemy's home province is when you set up the AI nations, so you don't know where they start when you set them to AI.

[Gandalf Parker]

You can use mapping commands set AI things like scales, pretender, etc. Even give them bonsues. Adding such things to your favorite map can be fun.