I know you brought this up in
my aero mods thread where I posted how I used shrinkable window film for a grille block. It worked OK for a short test, but was loosening up every couple of days after a week, so I replaced it with a studier material (from a plastic expanding portfolio).
I'm not sure the type of shrinkable film for boats and such is the same basic stuff used for window insulation kits. If so, my advice is: yes, use it for temporary tests, but don't expect it to last long. If it's thicker and stays taut better than the window stuff, it would be very useful.
