It would very difficult to commute to Syd from Qld. Sydney recruits are being told to expect daytripping rosters. You will need to be in Syd for 5am sign on 11pm signoffs and standby days. So you would only be able to return home on your days off. Commuting does not count as duty travel so you have to pay the fare yourself. Not to mention the risk of the flights from that port being full, which is high.