Well, since I had to touch it anyways...
Here is a /usr/pluto/bin/Diskless_CreateTBZ.sh that I am testing. I have included a simple option to not install the kubuntu-desktop package. The resulting MD works and is ~1G smaller. There is no desktop available. If you choose Start KDE I don't know what will happen, you're on your own. This is not intended to be a supported feature, but if you *really* feel strongly about not having kde installed on your MDs then you can try this.http://pastebin.com/KpEGER17
Copy it into a file on your core (mine is currently /usr/pluto/bin/newDiskless_CreateTBZ.sh) and chmod +x it. Then run it. It should work (I've tested it once here) but let me know if you encounter any issues. Logging is unfortunately disabled as it was causing strangeness I havn't worked out yet.
If it doesn't work then re-run your original /usr/pluto/bin/Diskless_CreateTBZ.sh to recreate your MD tarball and continue on your way.