Lately I've been debating building a "pistol" to keep as a truck gun. The only issue is where to store it in the vehicle. I drive a single cab truck so space is tight and I don't want it out in the open.

Ideally I'd like some sort of rig to hold the gun plus a couple mags on the back of my seat, so that in the event I needed it access would be quick.

Does anyone know of such an item? Or have other suggestions?