I don't have enough experience with this one to say anything too conclusively as it's not all that often the flow gets low on the G in the winter (and I'm not going to generalize isolated low-water experiences on other streams), but I've found that "moving water" and transitional holes which will produce under normal flows will not produce under low flows. I concentrate all my effort, then, on the prime long-haul holding areas, especially where I've caught fish under such conditions before.
On rivers like mine where fish are moving all the way up, I don't think it matters a whole lot "where" geographically, I just fish wherever the aforementioned holding areas exist (all up and down).

I toss a light jig with a cork float most of the time, and more spinners recently, knowing both hatchery and native fish are hanging around.
The afternoon fishing=warmer water/more active fish thing makes sense, and afternoon sun on the water in winter doesn't bother me as much as summer, but I still like to be stealthy, and sneaking up from the tailout at first light is about the stealthiest approach I know of. I've caught too many fish before sunrise under these conditions to let myself sleep in if I've got the energy to get out of bed.

I'll be interested to hear some others' input!
Andrew