We did Tasmania for consecutive new year holidays (each about 10 - 11 days). We did 3000kms the first year 2009-10 (anti clockwise) and 2500kms the second year 2010-11 (clockwise). Does that mean it is longer anti clockwise?
Not wanting to plan "your" trip but here is a possible 10 day motorcycle tour of Tasmania based on our 2 trips. We find that after 5 consecutive days on the bike we are looking for a non-ride day, others can ride every day.
But I do suggest you listen to Dennis's local advice.
As advised, October's weather could be anything - be prepared.
Day 1: Arrive Ferry and head east to along Frankford Road and Holwell Road to Tamar River region with visits to Beaconsfield Mine Museum, Beauty Point (Seahorse World and Platypus House) and down to Launceston that night.
Day 2: Launceston to Longford then to Poatina and up the Poatina Road then down to Miena (southern end of Great Lake) and then north to Deloraine (some gravel) and Westbury and back to Launceston (230kms). If you wanted to stay on the black stuff you could go from Miena down to Bothwell and then up the Midland Hwy to Ross and Launceston (330kms).
Day 3: Launceston to Scottsdale to St Helens (Bay of Fires) to St Marys to Bicheno. Mt Elephant pancakes south of St Marys and Bicheno Motorcycle Museum are must visits.
Day 4: Bicheno to Port Arthur then to Hobart. If you have a spare day then Coles Bay is a scenic place to visit and stay.
Day 5: Hobart to Oyster Cove to Cygnet to Huonville then down to Geeveston and either Tahune Air Walk or Hastings Caves then return to Huonville then up to Lower Longley then Huon Road (not Hwy) to Mt Wellington and then back down to Hobart.
Day 6: Rest Day in Hobart. Or if you are keen then take a day ride from Hobart up to the Gordon River Dam and back to Hobart.
Day 7: Hobart to Queenstown then out to Strahan. Morning tea at Tarraleah & visit Wall in the Wilderness and Lake St Clair near Derwent Bridge.
Day 8: Day Tour from Strahan either Gordon River Cruise or West Coast Wilderness Railway (both expensive).
Day 9: Strahan to Zeehan (visit the West Coast Pioneer Memorial Museum) then to Roseberry up to Wynyard and Stanley (The Nut).
Day 10: Stanley to Burnie onto Cradle Mountain (either via Ulverstone or down the Ridgley Hwy and Murchison Hwy and the Belvoir Rd). From Cradle Mountain to Sheffield (Murals & Scenery), Railton (Topiary) then back to Devonport to catch the Ferry. We felt to get value out of Cradle Mountain we should have done a hike but time did not allow for it but it is still a good ride and is scenic.
Another good road to ride is the Lake Leake Road from Bicheno to Campbell Town then a short trip south to visit to the old town of Ross.
Saturday morning in Hobart, the Salamanca Place market is always interesting, close to the docks - even though it is much better around New Year when all the yachts are there and the Taste Festival is on.
In the northwest there is really only Stanley (the Nut). IMO, Smithton has very little to offer the rider or tourist. From Wynyard it is up and back the same highway, so if time is limited I would leave out the north west and spend some more time around the Cradle Mountain & Sheffield area.
Also going over on the ferry, make sure they tie your bike down the way you want them to, not how some novice deck hand wants to do it. They prefer to use handlebar straps.
I always use soft ties (which I carry) on each front fork at the cross bar and then use their ratchet tie down to strap it down. Also pack a small 1 night bag for the ferry trip over so you don't have to carry everything up to your cabin.
Tassie is certainly a top class destination for a motorcycle touring holiday.
You will definitely want to go again.
Go for it