Hi James,
Yes, you can deploy you assignment with a small class number and
you should be able to pass. For may own experience, I have used only a few classes in my assignment and I have passed with a very good score in the class diagram.
And talking about the business classes in the class diagram, you should attempt that this approach must be used with something else in mind over only enlarge the classe number.
It is considered correct that an class diagram should be technology independent. But using business classes like EJB's in the class diagram it is not considered wrong. I have seem many people following the Cade's example for the assignment and they're using EJB classes in the diagram just because HE DID. But anyone really understand why you should put business classes with your domain model and why Cade's did.
Well, the short explanation is: You have to put business classes at the class diagram when you want to enphatize the DEPENDENCY between the business classes (an EJB for instance) and some domain classes. Maybe it is crucial for the application, document the potential impact of changes in the domain classes, and it's a good idea show that this changes will affect the business classes. Large and complex systems should use this approach everytime.
But, for a small application like the TRS (Travel Reservation System), I don't think that it is essential meet this requirement. For desing pourposes, you could hide this information from the classe domain model.
Anyway, this is my point of view. I can't say that this should be a rule for every enterprise project. Use the good sense for that!
Best Regards!