BTW, a few months back I ordered several bright orange plastic tarps (as opposed to blue tarps) from tarpsonline.com. They are just like the blue ones, but that wonderful bright orange color!!

The web site picture shows them as a dull orange color, but they are much brighter in real life - more like the page's background color.

http://www.tarpsonline.com/orange.asp

Now that's a real orange color. I'll bet they'd be able to see a shelter built with that from space

Seriously, I'd think that would be a great advantage. The orange would contrast well against grassland, snow, water and forest in the daylight. Once used to build a shelter, doubling as a signal is great because there's no extra work required.

Edit: I'm sorry, but I just found their yellow tarp. I think that I might see normally again in a few days.

Have you tried the solar sill? I've only ever found them to be useful in large numbers, near things like ponds. YMMV.

Personally, I hope to replace my simple plastic sheeting with Tyvek or Heatsheets by spring. Clear plastic sheeting, even in thicker weights, is a marginal item in my experience.