febootstrap now includes an image minimization tool which can remove some “non-essential” data, such as locales. (You can configure exactly what it removes).
The bootable minimal install is now around 16 MB. There’s still room for improvement, for example by removing shared libraries that are never used.
Even my realistic image, which includes LVM, NTFS, NFS server and rescue-disk utilities, isn’t too bad, weighing in comfortably under 32 MB: