|As Reddo said....water is the go. If you are flying across great tracts of the Gaffa, and go down, water assumes an enormous significance. You can live without eating, but water is important, amongst other goodies in the survival bag.
a plastic sheet to generate water through condensation is good too. All this stuff about knives to kill crocs pales into insignificance when faced with thirst. (If no crocs, read as kangaroos) Definitely I would leave the sarnies behind and take along a lot of water. Just remember which juice bottle you have used for other purposes.