A leaky heater hose can usually be shunted or repaired in a similar fashion by using a flush and fill fitting in place of the sleeve. There are also emergency fan belts which will serve to get you back to civilization. Well Equipped four-wheelers will carry the above plus a hunk of fuel line, axle and driveshaft U joints, a spare headlight, spark plugs, distributor cap, rotor, coil, tire valve stems with cores, radiator cap, and a starter relay. If you run ARB lockers, you might also carry extra air lines, o-rings, air line couplers, and bulkhead parts. Rolling Service Stations will carry all of the above plus axle shafts, ball joints, drive shafts, a spare alternator, starter, an electric fuel pump, both pressure and return power steering hoses, oil pressure and water temperature sensor sending units, and a thermostat.
Old parts can be a source of spares.
Next time you do a tune-up keep the old plugs and distributor cap as spares. Also remember that you can limp home without items such as thermostats in a pinch. Lay the tarp on the ground to keep yourself out of the mud and to catch small parts. The turkey baster can be used to move a variety of fluid, especially gear lube. The pail can catch fluid you need to drain, fetch water, and store gear.