Veral, your garbage bag idea is spot on. Earlier this year, I was assisting a DFG youth hunt in the high desert of SoCal. We got hit with an unexpected rain storm that turned into a snow storm pretty quickly. Winds were gusting to 25-30 kts. (I was an USAF Weather Observer so when I estimate the winds, I am dang close to spot on) Wind chill was around zero. I got soaked to the skin and was miserable. We had some heavy duty garbage bags that we use for bagging entrails etc. I cut a hole for my head and arms, pulled it over me and slapped some duct tape around the holes for may arms to keep the bag from ripping. I put my belt on over the bag and cinched it up lightly at the waist. I got warm right away and wind chill ceased to be an issue. I'm 6'3" and 300 lbs. It fit and it worked. When i got home, I took the bag/poncho and rolled it up tightly. I then put it in one of those vacuum sealer pouches that you use for the freezer. It shrunk it up so small it is barely noticeable in the pocket of my coat.