Ouch man, that is an ass whip.
I have a tool box on my truck/tow rig in which I always keep:
Set of SAE and metric 1/2" drive deep impact sockets up to 1 1/8" (for lug nuts, etc.)
1/2" drive breaker bar (non-ratcheting socket wrench for breaking nuts/bolts loose)
SAE/metric 1/4" and 3/8" drive socket set
Set of SAE and metric wrenches
SAE and metric allen wrenches
Wire nuts, small gauge electric wire, electrical pliers, zip ties, electrical tape
4-in-1 screwdriver, assorted pliers, vice grips, 3 pound sledge, gorilla tape, rags, rope, tire pressure gauge, 12v tire pump, tire plug kit
Stuff I usually have in there but not as vital:
cordless drill, cordless driver, hot battery, battery charger
big drill bit set with nut drivers/socket adapters for cordless driver, torx/star bits, etc.
assorted nuts/bolts/hardware
Stuff I need to add:
assorted automotive fuse set
1 quart 10w-30
???
I take this truck out to the ranch, etc. where I need tools much more often than I need them for the boat, but having my tools with me when I'm towing anything is my security blanket that gives me peace of mind.