Miner and myself are of the same shelter mind. One thing I'll add is that polycro actually comes in different grades or different thicknesses in mils. Same with Tyvek. FWIW I've made bathtub floors for under a tarp using the 1.5 mil Duck brand Window film. It also comes in .5 and .7 mils. I've made them in .7 mils but in my use leads to unacceptable durability. On soft sand they are OK if you pre screen the site for thorns, small rocks, pieces of cholla or Joshua tree blades.

Here's the .7 mil: https://www.duckbrand.com/products/w...-x-120-in-3-pk It's really wispy, the slightest breeze blows it around, and if a puncture occurs it quickly uncontrollably tears.

Here's the 1.5 mils: https://www.duckbrand.com/products/w...n-x-126-in-3pk I get 2-3 ground cloths out of this size. Cost is about $8-10 at WallyWorld. This still saves wt over Kite Tyvek 1443R.

It does shrink if left exposed to high heat.

It seems many backpack to reconnect to Nature, to decompress from off trail affairs. One way to facilitate that is through knowledge and wisdom rather than always being fearful, like of snakes, scorpions, bears, etc. Familiarizing ourselves with the natural environment and cooperating with it through awareness is a better approach IMHO rather than always attempting to dominate it in a consistent human centric mindset. There is a world of beauty beyond what is man made or known by man.