Excellent work! I think this is great (wait, this concept feels familiar. Wasnt I too lazy to do this?)
There are three things I like about creating MODs which duplicate the nations we already have.
1) MOD tutorial. Looking at one will be easiest to understand what it is doing. And making one for a nation you know well would be a great way to break into MODding.
2) The Challenges of the Experts. Those who feel that they are the ultimate player of nation XXXXXX nation but cant seem to agree with other ultimate players of XXXXX. Now they can go head to head to prove who is Ulm Ultimate! I can see some of the Ermor vs Ermor, or Arcos vs Arcos. Anyone want to test their "I play Pangaea like a poor mans Ulm" against my SuperStealth tactics?
3) No more bickering if two people ask for Ulm at the same time in a game. Just pick one of the unchosen nations to set the Ulm Mod to replace. (Isnt it limited to replacing land nations?)
Oh yeah, with the new command-line switch to set mods for a game, it should be possible to have the web server recognize and allow multiple Ulms in selection. And do the slight rewrite to slideit into an unused nation slot.