Reminds me of a "baker tent". Bill, with a few more feet of visqueen, you could enclose the front or make a porch. Does the mylar really do much for your design? I wonder if the dead air space between the mylar and visqueen does more than the reflective properties? I've built baker tents from cheap plastic tarps and sticks that worked very well. Good 'down and dirty' shelter.
http://www.cdaml.org/baker_tent.htm