One real positive for you: as Aussies you're heading into summer.
In the short term your body is going to want to eat. Try and make sure you've got a few more healthy but tasty snacks around. Fresh fruit of course. Just think: you've got all of those gorgeous berries coming into season, strawberries and blueberries are particularly good. Yes they might cost a little more but you'll probably going to be more likely to want to eat them, and the hiker hunger will wear off after three or four weeks. Apples are also great.
I quite enjoy having carrot sticks in a little water and lemon juice sitting in the fridge - I love the crunch. Others enjoy options like celery etc.
I try and make sure that I've always got healthy food options prepared ahead of time, it makes me less likely to snack on chippies, bread etc.
Eat plenty of salads with decent protein but minimal carbs. (Think chicken Caesar, Italian style with eggs and anchovies; Nicoise, Steak, Salmon, BBQ pork, grilled fish, etc, etc.. Go easy on the dressings, and look for less calorie dense options ! Balzamico and olive oil, lemon vinaigrette, etc).
I could easily serve you a different, tasty salad every day for a month; that said there are plenty of other options out there too!
Sushi, stir fries, beef strips with garlic, ginger & baby bok choy. In fact, if you looked at Asian and indian dishes..... .
Let alone all of the wonderful Italian options ( no I don't mean pizza!) .
Go easy on carbs like spuds, bread and pasta, eat more vege and rice dishes.
Limit portions. If you're the type of people that have to clear your plates, ensure you put less on to start with!
At the end of the day it's just a matter of consciously making a few healthy choices to start with, it will soon become a habit.
But then you already knew all of this, it's just a reminder.