Stephen, I agree with Charriot that there is no sleeping around the coast for vessels staying coastal. But I disagree on there is no reason not to do it, there are numerous reasons not to do it. Of course anything can be done but skippers must weigh up the risks and not rely on the view that someone will rescue you .
Going north you stick close to the coast to avoid the East Australian Current, google it or watch Finding Nemo. Here is a link to show you what it looks like.
oceancurrent.imos.org.au/LordHoweS/latest.htmlGoing outside the EAC is a long way offshore, 36? hours out? Battling against it is possible but it is 2-3 knots a lot of the time and with you doing 5 knots you can see it isn't a good place to be.
Close to the coast you don't have commercial traffic a few times, it is almost constant with fishing and other recreational vessels. Eden, Moruya, Narooma, Batemans Bay, Ulladulla, Greenwell Pt and Kiama are south of Sydney and all have fishing and recreational fleets. Sailing from Sydney to Queensland there are hundreds of small vessels that don't use AIS. E.g. Last year we had 2 fishing trawlers turn their nav lights on 200 metres from us in rain. We could not have seen them if they hadn't seen us and turned their lights on. That was off Norah Head north of Sydney about 5nm out. If you were asleep you would have been in trouble as they were recovering nets and unable to easily manoeuvre.
On those legs that can be done without proper sleep go for it. Take someone with you on the legs you can't do without sleep.