My setup is vaguely similar to H2O_Doc's "cargo bin thingy." I use plastic storage containers and some bungee cords. The lip on the bottom of the container "bites" into the carpet and keeps it from sliding around. I have a small one with flashlight, small inverter, &c in it that stays in the car and some other misc sized ones that I use as needed. The window shade cover keeps everything hidden so it doesn't look too White Trash-ish.
