Got the awning. It's a Suncamp cardinal size 9. The Destiny needs a size 11 to fit properly, but as this was extremely cheap, I will adapt it. The walls and poles are all brilliant, but the roof is another story I'm afraid. Mildew has got to it big time, and it seems to tear very easily, but I will get as much use out of it as I can.
The fact that it is too short isn't a huge problem. It will go all the way to the end of the bed on one side, with the underbed skirt acting as a draft skirt. The other end of the Dandy doesn't have an underbed skirt, so if the awning DID go that far, I would only have to make something to sort that problem out. As it stands, my awning will reach as far as the start of the bed wing. My plan is to bring the awning straight down at that point, and either velcro it, or just peg it tight up against the wall like a porch awning.
I've decided against the awning rail for this one, and have gone with Carls idea. I'm going to make eyelets(somehow) in the awning, thread the awning under the roof of the Dandy, and tie it to the roof poles. I'm going to do the brackets slightly differently though. I'm going to make 3 U shape brackets with a lip on them, and a hole in the lip. The bracket will fit over the top of the wall and the hook on the awning rail with slot into the hole on the lip. The other 2 awning poles will be held in place with the quick fit brackets that just push up against the wall (obviously, where there is a joist). I will post some pics when I get it done. Anyone got any advice on the awning roof?