I checked the ARB awning, the price is OK but the length is either too short 48" or too long 6.5'. Instead I got some aluminum U channel to attach above the rear window and will drill the legs of the channel and use clevis pins for the grommets in a tarp to hold against the camper and tarp poles to hold it out. About $50 total.
That is exactly what I did, shallow depth aluminum Unistrut. I got it from McMaster-Carr.
I don't have a photo with the awning, but I used a 6' length of 1x1 that I ripped in half. Sandwiched a 6x10 tarp between the halves and bolted it togther. I use two T-nuts that slide in the Unistrut and a thumbscrew to attach it and a couple of tent poles to hold the other edge. The two tent poles were the most expensive part of the deal.
However, this is not an ideal awning. It's pretty low so unless your truck has a ton a lift it might be frustrating. I also use an 8x8 EZ-Up that covers the rear door, but like kpherzog mentions, this takes up a lot of cargo space and is pretty heavy. So for quick trips the side awning is fine.