I'm getting to old to carry much besides fuses, lamps(light bulbs in today's world), three pex fittings, water and stinky slinky washers and/or "O" rings, WD 40, Kwikee lube in a can, lots of bar rags,wiper blades and mostly multipurpose tools like 6 in 1 screwdriver, Leatherman tool and of course the world famous SAE/Metric Spanner.
Specific function tools like a 7/16" combo wrench for the F connectors on TV cables, my curved jaw Channelocks for hose fittings and my trusty old 6" long tire pressure gauge. Those three sit on my gloves next to the door inside the rig.