Back when our toad was a Chevy Tracker, we put two Action Packer boxes behind the rear seat, one with vehicle related stuff, the other with a single burner stove, food, utensils, etc. I just threw a shelter half over them to "conceal" them. The shelter half could of course be used for all kinds of stuff. Now that we are tooling around in a P/U, in addition to a crossbed tool box, I just secure those Action Packers to a welded in tiedown with a chain and padlock. A second padlock secures the other latch. Won't stop a determined thief of course, but will prevent a grab and run...