I see we did a 4 night 5 day walk in the same valley, which will take you to the Mann River.
http://jackandjude.com/log/tranquility/There is a forestry road, Narala Road probably best with 4WD, high clearance essential, that takes you within a few hours of the River. Just do not go down the narrow last bit to the locked gate, no way to turn around.
Not shown in the above webpage, we've walked the Raspberry down the Corradoral to the Mann, then to the Nymbodia and out to Jackadgery in about a week. The gold mine is at Cherry Tree Creek. Easy walking just lots of it. Lovely place.
Over the hill into the Wellington is worth another outing. Up heartbreak hill, (forestry track) and off at the top to descend into Wellington. There's a 4WD track along the ridgetop making it faster coming back. I'm back at homebase for the Tassie winter, so if you need more info, just email. BTW Winter is best for these walks. No ticks, no snakes. No other people ever.