Good idea - I'm in for a couple of external screen stickers:
TuonoZone } Overlaid on a Union Flag or summat
Sparky }
(Can't edit this post right to show the rough design idea!)
If you are just trying to protect your paintwork and not wanting to fit stickers for the sake of it one of my vinyl suppliers sells the 3m paint protection film, if you wanted to make a stencil with dimensions of the area you want to protect and email it to me i could see how much the film is and sort you a cheap price out, I could also make a couple of files (gen1 /gen2) of the areas people ask for and make pre cut sets.