Converting rear sun shades to blackout curtains

Today, I am buying a W221 S 350 L that has most options checked (full nappa leather interior including dash and door panels, rear seat heating, cooling, memory, etc), and most importantly it has power rear sun shades.
The thing that has always bugged me with most car sun shades - they're literally here to block the sunlight, yet they're full of tiny holes! So, I would like to replace the fabric with a plain, full fabric, that can actually block light from coming in.
I don't think this would be really hard to do (remove door panel, remove sun shade module, take it apart, unclip the fabric from everywhere, use it as a template to cut the new one, then put everything back in place, but I'm curious:
Have any one of you ever tried this ?



