Well, after reading the many threads on here about rear storage units I decided to tackle my own. I grew tired of having to clean my dog before putting her in the truck, and my wife also complained about never having a place to put groceries in the rear cargo area because I had "shovels and toolboxes" laying around. I built the frame out of 1x4 wood and put plywood over that and finished it off with some outdoor carpet from Home Depot. I installed a trap door hook on the top to anchor my dog as well as a locking latch on the front. In all I spent maybe $125, but it turned out pretty well and my dog loved it during our road trip today.