Budget?
Pelican is the gold standard here, generally speaking, but it's all three figures for anything bigger than a cell phone box.
Rubbermaid has their "Action Packer" line. Pretty much just one of their general Attic/Basement storage boxes, but with a lid more like a cooler, and some reasonably decent latches and hinges for the lid. Pretty much purpose made for what you're asking. For riding in the bed of a pickup truck exposed to the elements.
Only Weather Resistant though. Not waterproof like the Pelican would be. But for something like improved campsite state campground car-camping, it would do the job with aplomb.