A Possible Solution Presents Itself
In searchin for other things last night, I discovered that KnitPicks has a new cotton/linen blend yarn out. It's called CotLin--imaginative, no?--and it's DK weight (5-6 st/in) in a range of acceptable colors, including a red that I like better than the red of the 100% cotton I currently have. So I've ordered a skein, and we'll see how it knits up when it arrives. If it's nice, Fire Dragon Year will be a summer sweater after all.
On the knitting front, it occurs to me that Dragonskin has decreases that I can use in the waist shaping; just do the two side decs without their corresponding increases, et voilà. I am also contemplating doing something mildly complex with the sleeves, but I'm not sure yet how it's going to work. We shall see when I have yarn to play with.