I've been following the survival kit discussions with interest. One part of my flying kit nowadays is to always have a flyfishing guide hoodie as my top layer (unless it's cold enough for a down jacket or similar). These hoodies are lightweight synthetics (designed for sun protection in the tropics) with extra long sleeves, with thumbholes at the cuff. They're perfect for all-day-long sun protection and fit over a ball cap, and under a headset, if you need to wear one. If I had to to spend a day or two stumbling around the desert after an outlanding, that's what I'd want to be wearing.