I've never tried that, but I think it'll be a really good idea. I've seen the blankets you're talking about, but not clear, just the blue for pools. Since the shadecloth comes off here for winter (I guess yours does too?), the clear shouldn't block very much light at all. I'm going to have to look into this. We're on nat gas, not propane, but still, if we can insulate a little better, it might make up for how much extra the shipping people are going to charge because of the price of diesel...