Why not just explore the Wellington Range for 2 or 3 nights. Get off the bus at Ferntree and walk up and under the Organ Pipes to Big Bend, Lost World..... then maybe camp a couple of nights near the top of Mountain River (nice sheltered campsite there).
Go across Connection area to Bonnet, check out the Cap, Myrtle Falls, walk over to Marian-Patrick area and back to your campsite.
Day 3 strike camp and walk out to the bus via Montague area, maybe take in Cathedral rock........nice and close to Hobart