A few years ago, I bought a toolbox that is actually a regulation 5-gallon jerry can that opens at the top and the front to reveal a pull out tray and two drawers. They are available on line. Paint it OD green, slap it around a little for some patina and it appears like just another jerry can. I have a GI jerry can holder I am planning to mount to my running board and it will be a period-correct after market mod. The jerry can/tool box even locks.
Same thing as this