Angie, welcome to the forum. The gas bottle manufacturer website should have safety advice. You should be okay up to the highest probable temperature, low forties.
Thishttps://www.rfs.nsw.gov.au/fire-informa ... -ban-rules
has the fire ban rules. In part it says:
"Can I use a gas barbeque?
You can use a gas barbeque under the following conditions:
It is under the direct control of a responsible adult, who is present at all times while it is operating;
No combustible material is allowed within two metres at any time it is operating;
You have an immediate and continuous supply of water; and
The barbeque is within 20 metres of a permanent private dwelling such as a home; or
The barbeque is within a designated picnic area and the appliance is approved by Council, National Parks or State Forest."
It is unclear if a bushwalking stove is the same as a gas BBQ. It may be that the above rule is about fixed BBQs, usually coin in the slot. The end wording is vague. Which council? How can a national park or a state forest approve anything?
There are meals that do not require cooking. If the walk is a few days then sachets of fish, dried vegetables soaked for an hour or so, jerky, salami and even tinned food will have to do.