Easier to list what I don't carry. I keep a suitcase, cold weather gear. Coveralls, gloves, watch cap, thick socks, change of clothes, blankets, in case I find a stranded parent with kids, which I have. Take it out in hot weather. Another case, change of clothes, all PPE gear, welding caps.
Shovel, pick, axe, machete, saw, chain, plywood, cables, serious come along, 12v metal air compressor, plugs for tires. Engine belt and tools to change belt. My last truck took a 15mm end wrench, beat into a certain configuration, I kept that wrench not with my other tools. I had a piece of aluminum, the leg off a broke lawn chair, system worked flawlessly. It would throw the belt now and then, but at 325,000 still ran like a top. Water, stop leak, which in Arkansas it is red pepper and horse turds. Of course all the things to make my flat tire experience as un eventful as possible. Two or three spares at times. Plus I have a lot of tools, but not really for my vehicle. You can't hardly work on these newer vehicles on the road. Maybe an alternator, but I keep that changed. Hose fix kit. I do keep a good radiator. Extra all fluids for vehicle. But I don't really need those because I keep them checked at the shop. But if your pire sturn leaks while off and away, good to have some juice for it.