I have a 2004 4Runner. I'm interested in a lockable box for the rear cargo area, which would take up about 1/3rd of the available space. I'm intending to store your typical roadside emergency gear but want it to be secured and lockable for other valuable items, including a laptop, truck gun, ammo, or anything else one might want to secure. I built one from plywood and 2x4s and it turned out okay, but it's extremely heavy at about 100 lbs. I'd like something of durable plastic that weights a lot less. OR, I once saw a product that replaced the vacant space beneath the rear seats with a drawer. Anyone know of such a product? OR, I'm considering a steel or aluminum full or pickup truck style lockable wing style or traditional lid. Any thoughts? Thanks.