88mm deep? While I’ve never measured the width of the door (on my car) it sounds a lot to me. Only thing I can suggest is you take a door panel off, and measure the available space - allowing for the trim depth, and see what size is available. Obviously do this before buying them, I jst hope you haven’t yet?
I have another thought too, but as it’s just a theory, I won’t go into that further.
I fitted these Focal 8" components to my NC, along with a 70w RMS amp under the passenger seat. I also have a fairly cheap Pioneer double din head unit, as I thought the factory fit one was pretty poor. The plastic speaker mounts actually have a line on them to cut out to fit 8" woofers. The sound is not as good as having a sub woofer, but it is way, way better than it was standard. They weren’t that much cop without an amp though. It doesn’t answer your question, as they are shallow, but pretty good for the cost, and easy to fit.