Reviving old threads is quite often informative.

I carry an 2GoSystems reflective Tyvek tarp bivy (36" x 87") and a silnylon poncho tarp. https://ca-2gosystems.glopalstore.com/products/trifecta?variant=5897656453 I have tested the bivy with a wool anorak down to 4°C, no wind; that's the limit of comfort without addition insulation. The bivy is about the size of a loaf of bread 4"Ø x 9.5" and the poncho tarp is about 1/3 that size. It sorta fits into my 750ml cup/pot.

I also carry a collapsible hiking stick. ON it I have wrapped a 6-mil drum liner, 750-paracord, 36# bank line, duct tape and snare wire. The cork knob on the top screws off so that I can attach a camera or binoculars to it.

Space blankets are not blankets and should never be used as such. They are OK for an hour and then gather a ton of sweat from you body. Their main claim to fame is their low cost. AMK's more specialized reflective blanket/bivies are OK but the complaint I have of them is that they are too small for 70% of the population! (Sorry, AMK, but I am not a 150 lb weakling.)

Tarps are great temporary shelters and if made of silnylon are very compact. But they are much less convenient above tree line if you need something to tie off too.