Hi bareroots
Unforntunately I dont know anyone in Tasmania. I am going there in december and I was going to try the wilderness society to see if they had any contacts.
They are sometimes involved with tree sits and protests. They may be able to put you on to someone.
http://www.wilderness.org.au/campaigns/forests/tasmania/
If you have any success let me know.
either way you will have a great time being in the presence of those amazing Mountain Ash.