just off the top of my head i would say get big Nalgene
jars for water..i have a quart size one that i fill up
with "canoe country" water and bring home with me for sips
over the winter and it's never got a "off"taste..
flashlight--how about a LED headlamp..working hands free
makes a lot of things easy..puting up a tent--cooking--
sorting gear..
food..for 72 hours i would use MRE's with some freeze-dryed
camping meals tossed in to use when you have water to spare.
but 72 hours is nothing..you could eat zip top cans of beans
and fruit cocktail..i think the SOS bars are for people who
see themselfs holding up in a cave for weeks..