Ground Cloth

I think there are many threads on backpackinglight on the topic of using window insulation film as groundsheets. I don't think anyone here is positive which industrial film polycryo is exactly (except the folks at Gossamer Gear). I'm not sure where Gossamer Gear came up with the term "polycryo", but it most likely they want to conceal the manufacturer. I also believe there are tons of similiar heat-shrink films available in the food industry.

There are some light options but not as cheap. Zpacks makes nice cuben fiber ground cloths. Silnylon is an option but might be too slippery for you.
I use polycryo material when I'm not using my cuben fiber. A 42"x98" piece weighs 1.7oz on my scale. I bought the Duck brand the last time I got it. Frostking is the better known brand and 3M also makes it.

http://www.amazon.com/Duck-281065-Indoor-Window–120-Inch/dp/B000NHW2Z6/ref=sr_1_1?ie=UTF8&qid=1390070648&sr=8-1&keywords=polycryo#productDetails

http://www.ebay.com/itm/NEW-Patio-Windw-Xl-84x110x42ft-Each-Window-Door-Insulation-V76H-077578018355-/350960378089?pt=LH_DefaultDomain_0&hash=item51b6de60e9

Also if you ever do get Tyvek the 1443R stuff is lighter than the standard house wrap material.

I use a section of Frost King OUTDOOR window cover for my ground sheet. Seems to work ok so far.