I can't remember if the SLT comes with the "Load & Go" system of if you're stuck with what the rest of us have in the rear cargo area. I have had the same compplaint and have attempted to flip my floor over to the raised and molded cargo bin but when I throw the chocolate lab into the mix I want the floor back. I currently have a "Big 'ol medic pack" that I carry in mine and have resulted int using a bungie cord/carabiner system on the side-wall D-hooks to keep it from rolling around.
I like the Bomb's idea and often look at what's avail for the Jeep Liberty as it's been out longer. I'll probably look into that option myself.
I notice that there are floor hooks as well, so there has got to be something in the mix cargo net-wise, I just haven't seen it come out on the mopar accessory list.