Ive got an Undercover
Flex Tonneau cover
which is the same idea. It uses up the factory bed rails so the sliding mounting points are useless now. I went and got a ratcheting cargo bar , something like this http://www.homedepot.com/p/Keeper-Ra...7#.UfXD0o3vubM
for my truck and it has worked out really well so far. I keep a lot of my stuff ( like boots, waders, other fishing gear, and even groceries ) near the tail gate so I that I just have to open 1 panel of my tonneau cover ,and this bar allows me to make a good sized cargo area using the wheel wells. It keeps everything in place and is easy to rearrange depending on what cargo you might be carrying. I found that it is also long enough to run from the front of your bed to the tail gate if you need to hold something to the sides of your truck.
Hell for the price you could probably get 2 and then make any size cargo area you would ever need
Hope this helped a little bit.