Heh, I have the advantage of a custom vehicle almost built for this kinda thing.
it's a 1994 tomos sprint moped converted to a trike with a pryer rear end, which i happen to be a master at repairing, and will run on prettymuch anything that the spark plug will ignite with a mere change of jetting.
(a 3 minute process, at most)
Spare parts run about 8-10lbs of kit, tools another 10-12lbs.
MRE's because cost/weight/space requirements.
Water in a cloth-type carrybag like the swiss use.
5 Gallons of fuel (at 212mpg, in addition to the 1.2 tank on it..that's a lot)
1 Quart of 2stroke oil (although any oil will do, even 10w30/10w40)
3 spark plugs.
Tent, bedroll, spare socks, the "standard" kit most folks go backpacking with.
Set of decent maps, binocs, common sense stuff.
Tool knife, combat knife, hunting knife
(some crossover, but a good knife is worth having!)
Probably a small shortbarrel 12Gauge and a decent revolver if they're handy, but my weapon of choice is actually a small crossbow with string silencers, since one can make 'ammo' in a pinch, and it's a hell of a lot quieter than a pistol.
My only real concern would be fuel supply, but without the alphabet boys screaming about it, i'm sure grain alcohol would be a little more available than it is now, and while it would increase maintainence due to the fact that it'll pit the aluminum parts if you don't clean and lubricate more regularly, this little beastie would indeed run on it.
-K