I was after a couple of cheap light weight pillows for another project (more about that later), so I sourced two of these on eBay for less than A$20 delivered (the pair). These pillows are approximately 18” x 12’ x 4” (45 x 30 x 10 cm) and weigh 100 grams.They have a delightful soft, warm surface, and clearly contain some kind of insulation material. I slept on one last night and found it to be the warmest, most comfortable hiking pillow I have ever tried!
The inflation valve is also more convenient than any I have seen on more expensive brands – it is so easy to adjust the pressure (with the touch of a button). The pillow was robust enough for me to sit on (though this may not be recommended) – Della split a Klymit ultralight pillow recently which she was using as a canoe seat – so that it has been replaced by a Thermarest Ultralight Camp Seat for that purpose.
As is usual with these inflatable things it is obviously made from some sort of heat sealable fabric. I was planning to cut them down for another purpose (which I will), but I am sure you could cut yours down to make it a slightly smaller pillow. I think you could get it to about 2/3 the weight without compromising its comfort or warmth. Even so, many people would be prepared to carry this pillow (which is about double the size and weight of my ‘normal’ ultralight hiking pillow (this one), just because of that.
You should never compromise about a good night’s sleep. After you have had one you will hike further and happier the next day than if you were tossing and turning on the hard ground all nght, for example.
https://www.ebay.com.au/itm/Ultralight-Portable-Air-Inflatable-Pillow-For-Hiking-Camping-Travel-AZ/113675329058?ssPageName=STRK%3AMEBIDX%3AIT&var=413798983665&_trksid=p2057872.m2749.l2649 This one from Amazon looks the same: https://www.amazon.com.au/Trekology-Ultralight-Inflating-Camping-Pillows/dp/B073XH2YND/ref=sr_1_1?keywords=hiking+pillow&qid=1557879557&s=gateway&sr=8-1