You're not the first one to think this would be useful.
Gandalf created a set of starter build pretenders for each nation for tutorial/practice game purposes. See the history of his trial here, go to Starter Files:
http://www.dom2minions.com/index.html
I was thinking bigger in my proposal (2 years ago) that never went anywhere. I still think an online repository of pretender builds would be great, and you could have it pick some at random and download for use in your SP games. Here is
the old dom2 thread where I tried to stir up interest.
Sill