It's all about the 3 B's: Blanket (mylar) Blade and Bladder. Gimmee those 3 and I can survive anywhere on this planet outside of the polar regions. Anything else, with exception of water purification, is mere but often welcome surplus. Water puro is in a class of its own, which you immediately appreciate once you suffer. Nothing like having it all evacuate from both ends simultaneously in a weakened state. That truly blows.
v^2