In regard to the original idea, I think it's true that there isn't a massive drive in marketing towards lightweight whitetail clothing. That said, Kuiu's Super Down Haven mentions it. I have not used or handled the Super Down Haven.
"As the first of its kind, the Super Down Haven combines an innovative down-proof, windproof, and ultra-quiet knit fleece with our legendary Quixdown insulation, making it the warmest and lightest late-season whitetail hunting jacket on the market. Down insulation provides unmatched warmth-to-weight ratio, but it was previousely unsuitable for whitetail hunting due to the loud fabrics—until now."
Bibs weight: 2 lb 11.6 oz
Our Super Down Haven Warm & Quiet Hunting Bib in Valo is the industry’s warmest whitetail bib, plus it's windproof & water resistant. Get it online from KUIU.
www.kuiu.com
Jacket weight: 2 lb 7.9 oz
KUIU's Super Down Haven Hooded Warm & Quiet Hunting Jacket in Valo Camo is the industry’s warmest whitetail jacket, plus it's windproof & water resistant.
www.kuiu.com
Oddly enough, their Proximity set is lighter, but I don't think any mention is made to that in the description...though I may have missed it. I used the Proximity set on all cold days last season, some in lower teens with high winds. I used a puffy under the jacket along with normal base/mid layers. I was impressed with it for cold weather sits.
Proximity pants (not bibs) weight: 2 lb 3.2 oz
Proximity Insulated Hunting Pant are engineered as an ultra-quiet system for cold weather hunts and built for close encounters. Available in Valo Camo.
www.kuiu.com
Proximity jacket weight: 2 lb
Remain undetected during close-encounter situations in warm and cold-weather conditions with the Proximity Hooded Insulated Jacket. Available in Valo Camo.
www.kuiu.com
I noticed some folks mentioned compression/stuff sacks. I usually use them when packing a lightweight lock-on (LW .5 or Retrograde) for hikes in. It's an easy way to compress, reduce bulk, and make a weight that's easy to attach to the stand with no snagging or load shift. I've attached them loose as well but prefer the compression sack.
Related to carrying layers in, near the end of last season I used an Eberlestock Vapor 2500 attached to the stand. It worked very well with the straps/buckles that come on it. I need to use it a fair bit more but it will probably be what I use next year.