[Hectic]

Advising against a pencil and paper isn't that good of an idea.
say it's raining out. You think a sharpie on a dollar store note pad will work? NOPE.
I carry a pen (fisher space pen, cheapish, refillable, writes upside down and in extreme heat and cold) I carry a pencil (never fails so long as there is a knife or rock handy in case of breakage) I carry China markers (great for marking on maps that are in a clear map pack, something changes wipe it off and wrote it elsewhere) and lastly a write in the rain notebook (mec has em, they are self explanatory, I can (with the fisher pen) write while swimming, no joke, and all my notes and diagrams and field sketches of areas hold up in any extreem (it's a sniper thing but still handy for other Intel notes and keeping track of timings and such.
For a 12 hour game you don't need as much. A few MRE's and some heater packs (bring extra for making coffee in water bottles while away from a fire or stove Google combat coffee for info) goretex socks are a savior, over cotton or wool but just extra socks are fine if your not a swamp stalker like me)