I've never carried one anyway and my understanding is, that certainly for the last few years is it hasn't been a legally enforceable requirement anyway. I've never bothered with the helmet stickers either and have never heard of anyone getting grief for that either. Every year there seems to be some new rules issued that are for the most part quietly ignored by the French public and police. I dare say that if you're caught doing silly things they may look for reasons to make things as unpleasant as possible but I'm sure French cops have better things to do than harass tourists. That's certainly been my experience over the last 40 years.