I don't have one on an Extended E-series but I would if I still had an E series. I do have one on a crew cab full size truck and love it. It's the older Rhino Rack batwing but is long enough to cover the whole tailgate of the truck and up the passenger side to the middle of the cab (b-pillar between front and rear doors).
I will soon be replacing it with a longer one though since there are so many available now.
You can easily mount any of these to Ray's (1der's) awning brackets sold on this site. I would be very careful with any of the pole-less ones though. Given a little wind they might tear up or bend rain gutters. My experience with these bigger awnings is that I'm just not willing to try to use them without poles, ropes and stakes. The bigger the canvas the bigger the sail and all it takes is one gust to total a very expensive awning, brackets and perhaps vehicle.
Here is an awesome and comprehensive thread on the latest and greatest from Expo: