I came across this company Kookabay who will make pillows to your requirements and they also do a lightweight range of sleeping mats. So unless i come up with something else i may be making an order.
It was interesting to see that the sleeping mats and pillow are indeed quite lightweight and pack size is tiny so i thought i would share it here. Unfortunately the website doesn't give information like U vales etc. but a quick email would resolve that.
If you are in the market for a new mat/pillow duo, you might want to consider these although i know that ordering from the US can be a little expensive and takes time.
Below you will find a list of weight conversions from the US ounces shown on the Kooka Bay web page to grams..
Mats:- 72"x20"x2.5" Mummy 354gr
60"x20"x2.5" Mummy 289gr
72"x20"x2.5" Rectangular 422gr
60"x20"x2.5" Rectangular 354gr
46"x20"x2.5" Rectangular 272gr
Pillow 12"x7.5"x3.5" Inflated. 37gr