Notice how the hair wings in the photos from the excellent hair wing tyers have the wing end a bit before the end of the tail? This is something that every very good to excellent hair wing salmon or steelhead fly tyer I've ever seen (or saw his flies) does.
Gary's flies are superb (even though he doesn't think so) and great examples for proportions and amount of material to use. Sparse is better than heavily dressed both for hackle and the wing.
Truthfully, any hair that is long enough can be used for the wing on a hair wing wet, you just have to remember to keep it pretty sparse if you use bucktail, bear, or calftail. Also, I never stack the hair I use on a hair wing because stacking the hair creates a "paint brush" effect that I don't like. I simply even up the hair in my fingers to the degree possible and tie it in. Doing it this way (without stacking) creates a nicely tapered wing that is nicely tapered and streamlined.
And if you tied in different colors of hair, it is possible to tie a hair wing, mixed-wing salmon fly, just use a wisp of hair for each color and stack the colors one on top of the other and tie in each wisp of hair with not more than 2 turns of thread to keep bulk down.
Another think I do with my hair wings is I always use a fully wrapped hackle, never a beard hackle. The fully wound hackle produces a very different, three-dimensional, and more subtle action when fished than a beard hackle. And I also tie half of my wing in and clip the butts before I tie-in and wrap my collar hackle. Then I tie in the other half of my wing after the hackle is wrapped and tied-off. This produces a much neater, smaller head, more durable fly with less bulk in the wing, and also helps the wing "work" and "move' a bit more when fished.
Oh yeah, I never use rayon chenille on my hair wings. If I want chenille, I use Alec Jackson's method of producing a chenille from a piece of oval tinsel and Ostrich or Peacock herl (dyed or natural) because it doesn't go dead in the water like rayon chenille does. The chenille produces by Alec's method means it takes a little longer to tie the fly, but the fly swims much more seductively.
My favorite hair for hair wings is Fox. For white wings I use white Artic Fox, for most dyed wings, I like Artic Fox dyed to the color I want. However, other fox species make extremely nice wings too. Instead of grey squirrel, I prefer to use Grey Fox because it is a bit crinkly, longer in fiber, has more distinct barring, and when 1/2 of the underfur is combed out, it produces a wing that is denser near the front of the hook that naturally because much less dense (this helps enhance the streamlined look, especially when wet) out near the tips of the wing.
If you want a translucent hair, you can't beat polar bear, unfortunately, polar bear is illegal in the USA unless you can prove it was brought into the lower 48 prior to January 1 1972, or have a US Fish and Wildlife permit (or certified copy) granting permission to have the hide the hair was taken from brought into the USA. Otherwise, you are opening yourself to a huge fine with possible prison time in a federal prison along with a federal felony. Definitely not worth the risk.
However, a decent substitute for polar bear is Mountain Goat hair. The downside is that this hair is not easy to find, is not stocked by fly shops because of the difficulty in finding it, and pretty much has to be procured from someone who has killed one hunting that is willing to sell or give you a piece of the hide, that he is most likely going to have mounted as a trophy because they aren't a lot of Mountain Goat permits given out in any given year.
