For a ground cloth, I use the ‘indoor’ polycro. It’s easily ½ the weight of the ‘outdoor’ polycro. And they last me easily 100 nights. But for a tarp, the ‘outdoor’ version looks tough; though I’ve never tried it tarping. A tip of the trade: let it sit out in the sun before you cut it to shape. You don’t want a perfectly cut ground cloth shrink on you while backpacking (because of sun or hot backpack).

-Barry