Hi,
Google made changes in relative path inside of KMZ, so simple zipping does not run anymore.
Changing the relative paths to absolute in all generated KML files should probably do the trick for KMZ.
Why do you need KMZ?
Isn't it easier to upload the generated directory with KMLs and tiles to an online hosting and distribute just a small KML with a NetworkLink to your online doc.kml?
Google Earth is anyway not usable without Internet connection so I don't see a reason why to distribute the complete rasters for maps to everybody.
Any web hosting is suitable - from cheap LAMP / PHP unlimited hosting providers to global Amazon S3/CloudFront.
You can even upload the data for free to Google Drive or DropBox for hosting.
Petr
P.S.
We may reimplement the Google Earth output from MapTiler to use the native tiling system of Google Earth - we would get rid of the KMLs and displaying would be faster (no overhead with KML parsing and loading, just the raster data tiles). The native tile structure is flat, so it could possibly run as KMZ after direct zipping, if generated together with the KML files on request. It would be possible to do if there is a customer for such a development.