I just tried this out today after messing around with some amsteel i bought recently. I went ahead and made a couple soft shackles using one of the pictorials here on HF and while fooling around a bit I discovered that putting them around the bunched ends and sliding them towards the center lessened the amount of slack considerably.
Now I have never seen or used snakeskins in person so I have no reference, but I know that you amsteel addicts out there have a couple extra soft shackles on your kit, so next time you pack up just slide them on and see if it doesn't tidy up your next hang a bit.
If I can't get the HF pix to work here is an Imgur album. http://imgur.com/a/qMVOo
In one of the picture I show how I loop the adjustable loop of my whoopie sling around the buckles of my double nest so they don't get lost in the bury while inside the sack.