Here's a hint. I finally got everything installed with 1der's brackets. It worked great, but the awning rattles like crazy. It's as if the awning itself won't close tight enough. I did some research and a bunch of people will get a couple 24" long velcro straps to keep the awning closed tightly. It completely stopped the rattling.
I would like to purchase Z brackets for a Fiamma awning for a 2007 GMC SMB. Is it too late to join your June buildout of parts? I can pay right away.
Unfortunately, the brackets are designed for the Ford Econolines. I have not tried to fit a set to a GMC/ Chevy van to see what mods could be done. These brackets require a horizontal gutter configuration the Econoline vans have. I think the GMC style gutter is more angled or nearly vertical.
If you are local somewhere here in NorCal or SoCal, we can get together and see if these might work. It would be a long shot.
Beastie 3: 2002 7.3 EB Cargo: Agile TTB, CCV Mid Top, Custom Walk Through, Lots of stuff added. BlingMyRig.com