Maybe hire an artist and make a painting/picture that represents your book? Images don't need translation.
You can still market your book in France, even if it isn't French. It's possible to make it onto those bookstores still =) If you are dedicated to your entire book in French, though, you may want to hire a translator that knows the language well.
Actual marketing options for France are limited ( I’m assuming you are self pub so billboards newspaper etc are out) as it stands french Amazon doesn’t carry ads they are slowly expanding advert to other territories but .fr isn’t there yet. Facebook ads are about the only decent option in terms of language, is the book a translation? If not you might want to market in English since it will only be of interest to English speakers.
