hi james,
nice flees! Yes, there's a lot of waste if you just use the tips of big feathers.
I have used the longer barbs (nearer to the base of the feather) as tails - they are very floppy/mobile, and fragile though. I use them on spinner patterns where being deid is a good thing.
Generally, I tend to just bin the discarded bits, i'm afraid.
You could probably make some dubbing out of the CDC, or use them to wrap a CDC'n'elk type body. should work well enough.