Bali to Darwin at that time of the year is normal and finding a boat to take you from Benoa Harbour to Darwin at the end of all the rallies, should be possible.
However, at thet time of the year in the southern hemisphere, the south east trades are blowing strongly and relentlessly; which is brilliant for people wanting to get from New Zealand to Bali, but a real bugger for anyone wanting to go the other way.
Typically, the northerlies blow, making it a decent trip from Darwin to Thursday Island and down to Brisbane in November during the transition from the Dry to the Wet monsoon season.
It can be done, but it won't happen in one single, easy, downwind run. It will take several months, probably on a succession of boats and it will be wet and uncomfortable.
"if at first you don't succeed....Redefine success"!