I need to up my game in the toolbox department, but right now there's stuff like a spare cap for the water fill, a voltmeter, a variety of electrical connectors, wire and tape, some plumbers tape, duct tape, locking pliers, vise grips and a small hammer. Also a copper pipe-cutter and some spare sharkbite connectors for Pex, and tucked away in the trailer is a long piece of pex, just in case something happens on the road. Oh and of course a rivet tool and a variety of rivets. A multi-tip screwdriver, and a leatherman multi-tool. I think that's it. It all fits in a small box.
I feel like I still won't have whatever I need next!