Hi Andrew,
If its any help, for charters into that area I work on a MINIMUM of 75% reserve. In other words I'm planning on getting home with just under half a tank. You can get caught in conditions where your fuel consumption doubles.
We had 1 trip north into Shoalwater (from Yeppoon) with research guys and we weren't sure whether we would get home, punching into SE 25 knots, our contingecy was a run to Mackay....after a 2 day wait at Stanage, we ended up in Mackay. Good fun surfing down 5m waves 10m apart(or thats what it felt like).
I don't think the other guys meant to be cruel, its just that its remote and you need to be very careful (your phone won't work, no mechanic and possibly no VHF in some places)