Hi ya Bradley.
There are heaps of Australian route creators out there in Trainz mate.
But one thing you must respect is,... that they may all be busy, creating the routes that mean something to them personally.
To create a reasonable route from scratch can take up to and at least 12 months of time and effort; that is unless they work at it 24 hours a day. And you really can't expect them to do it for nothing.
If you have a passion for Tasmanian railways, and you have all the DEM maps, measurements, assets, rolling-stock, etc,... then why don't you have a go and try to build it yourself.
No one will have a go at you for trying, and if you post regular screenshots as you do it, you will find much more support coming your way with tips and advice. This is a learning experience for us all.
And remember, the greatest reward is when YOU complete it,... then design a few sessions to go with it and then get all the trains to run on time.
When THAT route is finally released, you know and everybody else will know, that it was done by YOU. That is precious mate!
Now back to my Sydney route.
Cheers,
Roy