The GHB is pretty much loose in the back seat.
The clothes, boots, and other stuff is under the back seat or behind it (quite a bit of room behind the seat).
The extra gas cans are only when going on a trip, and those are bungeed under the cargo net. I don't normally carry them.
Pistol and Ammo is in the center console.
GHB (Get Home Bag, or BOB)
Get Home Clothes (change of clothes, with lots of pockets, already loaded with GHB items)
Hiking Boots (to change into from work shoes)
Pistol/Ammo
Copies of Important Papers, Maps (in plastic bag)
Tarp (8'x10' Green, Medium Duty, usually for covering loads, but will take with me if leaving the vehicle behind)
_________________________
Overnight Bag (change of clothes, toiletries) - This is for just mundane, non-SHTF reasons. It's come in handy a few times, like when driving a lot, and I just get too sleepy, and need to get a Motel room.
Spare Pillow (same reason as above)
OTC Meds and First Aid Kit (glove compartment, just nice to have handy when out, allergy, aspirin, ibuprofen, acetaminophen, stomach medicine, cold/flu/sinus, cough, etc.)
_________________________
CB Radio
Collapsible 5 gallon water bottle (in a SHTF situation, I'd try and fill this at a gas station or something, if able).
Toolbag (common auto tools, wrenches, sockets, screwdrivers, pliers, etc.)
Duct Tape/WD-40/Tail Light Tape
Spare bottles of oil, transmission fluid, wiper fluid, fix a flat, rain-x, etc.
Bolt Cutter (in case I need to drive through a locked fence)
Hydraulic Jack (just easier/stronger than a standard scissor jack)
Full-sized Spare Tire (not a donut, not that it'd work anyhow on a dual wheeled)
Cargo Net for truckbed
(2) 5 gallon gas cans
Fuel Siphon Kit
Slim Jim/Car entry kit (my wife used to always lock her keys in her car)
Camo netting (to hide it in case I have to ditch it, come back for it)
Jumper Cables
Portable Jumper Unit
4 Way Lugnut Wrench/Tire Iron
Bungee Cords, Ratchet Straps, Paracord (usually for securing loads)
(5) Quality filter masks (never know when driving through area with a fire, etc. or of course, SHTF reasons)
Roadside Emergency Kit (flares, etc.)
If I have the horse trailer with me, even more, as the living area of the trailer has cabinets that are loaded up with food and supplies (just for overnight horse events, etc.), and a big storage area under the seat, and even a portable toilet and mini fridge (propane powered). Fold out chairs, a fold out awning, etc. Of course, this is unlikely as a SHTF event is more likely during the work-week, when I'm solo, and miles away from home (and without the trailer on).