...Plus you can install in inside with SD card getting out of floppy slot just like the real floppies
Apart from that, you really can't keep the floppy (not even if you hacked a laptop slim one to mount). The height is the issue.
Flat Cable or custom PCB to move Denise socket from the original A603 position could be made, but I seriously doubt if the quality would be okeish due to noise. You can always try it ofc, but then again... where you could put it inside??? Have you seen the room available?
Imho get an HxC SD Floppy Emulator and stick it inside, or jumper ACA and use an external drive as DF0. Slick and nice solutions both