Unfortunately in country NSW there are no rail trails that will allow a route to be ridden that's longer than 6 kilometres, yet.
Once you take on the SW Slopes and the Central Slopes, particularly the SW Slopes, the climbs can be brutal. Between Tumbarrumba and Tumut the climbs are definitely brutal.
I cant see how going to Musselbrook can be simply done unless you stay well west of the Divide. As you are aware, you have to cross the Divide. Have you considered going due north. At Lockhart go NE to cross the river at Jerry Berry State Forest and north again around the Weddin Mountains on their western side to Grenfell then Canowindra on Canowindra Road to the Escort Way to be west of Mount Canobolis. At this stage of the tour no mountain will be an issue to you, now head east.
From Crookwell or the Black Springs route towards Bathurst, climbing out of the Valley of the Abercrombie River ... is along walk with a laden touring bike, fun. This is where sympathetic farmers stop and ask you if you want to throw your bike in the back of their Hilux or Cruiser.
Not to send you away from the BNA Forum but have you been to crazyguyonabike? If you aren't familiar with crazyguy, do a search for the individual towns that you have mentioned, and someone will have been through them with useful comments ...
https://www.crazyguyonabike.com/doc/loc ... pe=journal If you go to the BOM site, there are wind roses, with historic wind data that can give you a broader indication of the regional wind conditions ...
http://www.bom.gov.au/watl/wind/ and there is also Forecast Wind ...
http://www.bom.gov.au/jsp/watl/wind/index.jsp Some good possibilities for the later stages of your route, courtesy of cycleAustralia.info
The Central Tablelands ...
http://www.cycleaustralia.info/cycling/ctnsw/ Wollomi ...
http://www.cycleaustralia.info/cycling/wollemi.htm I'll be on the SW slopes tomorrow for a couple of weeks looking for ways to across the mountains, through the State Forests and National Parks, out in the Back Country. I'm expecting to walk a lot.
Good luck.
Approaching Tumut.

Warren.
"But on steep descending...Larson TT have bad effect on the mind of a rider" - MadRider from Suji, Korea 2001.
"Paved roads ... another fine example of wasteful government spending." - a bumper sticker.