I know I'm late to the party, but just a little info on the nomenclature. The "C" channel for those slide in/out awnings is called Keder Channel and the Keder Slide stuff is available at pretty much any outfit that does repair or fabrication of RV awnings.
I never liked the factory Fiamma awning so I removed it. I didn't care for it being in the way of the trailer door and rubbing against the top of the door while opening and closing it, or walking into those stupid brackets all the time. We now have a Clam screen shelter that we use if we're going to be set up somewhere for a few days or more, but If we are only doing a night someplace, I'll just string up the rope and pole awning in the Keder track I installed on the side of the trailer. I bought the aluminum one, but they also come in plastic as well. I used several 1/4"x20 stainless nuts and bolts to mount it along with marine grade sealant in the holes I drilled. If you don't want to drill holes in your trailer, they have some very strong 3M brand double sided VHB tape which some folks have used to mount the rail.
Awning Rope & Keder Welt
Keder Awning Rail Insert