Another discussed on ExPo
http://expeditionportal.com/forum/showthread.php?t=7339
Post up some details of what you had in mind.
Now I like that.... I would just add some bars that slide out from my roof rack for the supports... HMMMM
For X-mas my wife bought me a ground cloth for a North face tent to use for a rear awning on my Jeep LJ. I used North face for the color but the material seems like it will work perfect for my application, easy to stow and not so weak it will rip.
I will give some feedback after a couple of feet of snow melt and the grass turns Green.
Well the rear awning has worked out great, we have had rain and tested it fully, both the ease of set up and stowing is simple and easy. With my 1" tent poles slipped into the rollbar brackets I can use the soft top rear window for a small dry area. If rain gets heavy the awning sets up very quick, the rubberized side of the ground cloth grabs the soft top material and stays put...I bought a larger size to cover the side windows for a little more privacy and to go with the 3 front sun shades I use.