I hope no one is offended by me posting this in "Gear" but I stumped onto something that would only make a UL Backpacker laugh who has tried to convince is wife/GF to give it a try.
After years of "Only if you will carry a big fluffy pillow foe me". I have found the answer.
I was in a local sporting goods shop looking at he backpacks and luggage when I spotted the "void fill device" they use to keep the suitcases looking their very best. And I found this delightful device. Inflated is 12" x 16" it weighs less than an ounce the fill system requires a straw and is ingenious!
Best of all they sell em for 33 Cents! (Minimum order of 100 — crud)
Here are two One inflated one deflated
http://www.worldpackagingco.com/Air-BladdersVoid-Fill_c_153.html#.VQdQ1RDF-zs
