3. Polycro was a bad call for the 2x2-ft section in the head area. It ripped almost as soon as I opened it up and tried to drag it just a few inches with my pack sitting on the polycro section. I'll replace that section with more of the soft Tyvek.
Must have been some cheap brand to rip that easy. I'd used a piece (Duck brand I believe) for a groundcloth for several trips (some on rocky sites) that held up quite well until I sacrificed it to bundle up 15+ pounds of trash I hauled out.
However, another piece ripped the first time I used it. That may have been Ace brand.
Nonetheless, I can't envision how you're using this, and the head end is not where I'd want to since it's not at all breathable and you'd have significant moisture from your breath there.