To add onto my dad, we carry:
Ice chest with drinks and 2-3 days worth of food.
Camelbaks with 3 liters of water each and some basic survival tools (poncho, lighter, first aid kit, etc).
Change of clothes, including shoes.
Heavy duty jumper cables leftover from our diesel f250.
2 Shovels.
2 Crowbars (large and small).
3 .50 Cal ammo cans to store tools.
Socket sets, complete (in 3/8 drive and 1/2).
Channel Locks.
Vice Grips.
Full roll of electrical tape.
2-3 rolls of duct tape.
Power drill and drill bits.
Power inverter and shop light.
3 gallons of radiator fluid.
3 quarts of 10w-40.
One quart of PS fluid.
One quart of brake fluid.
One quart of autotrans fluid.
Whatever is left in the wiper fluid container.
Previously mentioned boards.
Metal loading ramps.