I know Cygnet and that area as I spent a bit of time there in early 2008 (mostly Ranelagh, Huonville, Geeveston). I particularly love that part of Tasmania especially for the waterways. Nearly bought a property (200 acres) there, but the timing wasn't right for me at that stage.
One of the Tassal processing plants is in Huonville if I remember rightly, and that area is especially picturesque during the apple season.
Good luck with your sale and the pest extermination.