Unfortunately the lesson plan is very specific with the requirements that have to be met. We cant change the routing willy nilly. Yes we can go in via Station Pier or Westgate every time, but come the test, ATO's want to see a commercial plan. That is direct thru CTA.
A commercial plan is one that gets you to where you want to go. If that means tracking via C and D to get from A to B then that is what you do.
Are you aware of the STAR that uses waypoint SHEED almost directly over Essendon at 2500' for runway 34 at ML? Basically, when rwy 34 is in use, your track at 5500 is taking you straight through the ML IFR circuit and you will want to be descending to land. As mentioned above, ring the controllers and ask them what routing you need to use to get clearance from YBLT to YMEN. That is what a commercial pilot would do if there was some doubt over getting a VFR clearance and that is what you should be teaching your students.
To give it an IFR perspective, do you think an IFR pilot would be able to plan direct YBLT to YMEN, or do you think perhaps they might have to check the ERSA for the route requirements and follow them?