Back again!

I spoke with my sister and she had a few suggestions.

She thought that the 3 places you had chosen were great.

Mt Field: Unless you are super fit, don't bother going up to the Tarn Shelf and Mt Field West, but spend your time walking around Lake Dobson to Twilight Tarn and the little museum there.

At Port Arthur, go to Tasman Arch and do the Clifftop walk to Waterfall Bay. Don't bother with the Fortescue Bay/Cape Raul walk as you won't have time.

She said that Bruny Island is great. She mentioned the Lighthouse there and a walk from Adventure Bay round to the Cape. She also has heard that they do boat trips from Adventure Bay out to see the seals. Apparently, there is a great tourist info service at the Ferry as you arrive at Bruny which will tell you all you need to know.

I hope that this helps a little.
Have a great trip,
Sue