I've been trying to set this up myself but I've had just an endless stream of crashes and don't have time or skill to fix them.

The idea I'm pitching is this, load the Gigantic Manifest Destiny Map

Then add as many US state Civilizations as seems like a good time. I tried to get this to work with the 42 Civ mod, but couldn't get compatibility with the map.

Then I'd add Virginia, Alaska, Illinois and many other states. I would also add Cascadia, Quebec, Mexico, Texas, Cuba.

The map editor kept crashing while I placed cities, but I was able to put down settlers. I was able to start the game, but about 10 turns in the game crashed. I tweaked some mods and then it couldn't even load without crashing.

So, if anybody wants to try modding this, I'd be thrilled to see the results! Here's screens of the setup I had. I made some tweaks to the Pacific NW and west coast to make it more accurate, and used the continent painter to make things look more diverse. I also tried to add some expansion support mods (to allow for bigger empires)

http://imgur.com/a/gl6Mj

Cheers!