That's really what the model field does: it specifies the class name. (It's a legacy term, so I cannot change it.)
If you need a library to manage users, you should probably name your library User_Manager. It just makes more sense logically. It's a library to manageusers. If you name the library user, then it's a user to manage user_models? ;-P
And as for controllers, the common solution of using the plural form for the controller works very well, and is usually only an issue for words that don't have a plural form.
In general, I am strongly averse to adding options like that: it's like the ability to rename the id column, or not have id be an integer. These options would benefit very few DMZ users, and would significantly modify the code (breaking a lot of simple, hard-coded strings into more itty-bitty pieces). Plus, it wouldn't help with the relationships, because the only short form for the relationships is to put the classname as the relationship name. How would DMZ know which class you meant?
But mostly, it's that you are trying really hard to work around a self-created problem. ;-) It just doesn't make sense to have the model and classname be different.