Michael,
I'm so sorry you got that impression from the ticketing page, as that was the opposite of my intent. The buses are only running from Launceston, as was detailed on the Railscamp site:
http://railscamps.com - I am perhaps guilty of not ensuring the exact same detail was included on the Eventbrite page.
The reason for this is that Launceston is serviced by a "greater" variety of direct flights, from Melb, Sydney and Brisbane.
The camp site is not far from Devonport Airport (15km, so 15 minutes by cab maybe?), but we aren't due to officially arrive until after 3pm. I should be there from 1pm though, setting things up. :) Alternatively, you might be able to meet up with some of the road-trippers arriving that morning on the Spirit of Tasmania and get a lift from them?
If any of this causes you a major hassle, just drop me a line directly and I can see what we can organise.
Cheers,
Warren