Since I would put them on the rear door windows, they should be OK. The rear windows are rarely used. As far as the thickness is concerned, are they thinner than the decals/stickers the decal makers use. I got both the SVT for the rear doors and
www.contour.org stickers from one of them. I think they may made of vinyl. Of course they can't make the oval for a reasonable price so you're safe there. I'm "assuming" that sun, rain, snow, is not going to make them peel or fade? I'd like to get these, I just don't want them to deteriorate in a year or so.
PS> Could they be used under the hood? Would they take the heat?