I used to settle for the 2 garbage bag and duct tape solution to shelter/warmth, but in my dotage I prefer a bit more insulation now, so based on everyone's recommendations, I bought and have used the AMK heatsheets and bivy's, and they are just enough to make it AOK.

Oh, and I lug a small tarp/paracord just in case of rain, about a pound's worth of weight.