Here are the pinouts I've determined so far on the hidden bottom connector of the i7, for those interested. Is such a connector present on the E-series?
No -the connector is an internal FFC con.
You may find a second UART - on bootup it only throws out a few chars.
Also worth a good look through the FW update file, if available.
The PDF linked from the PDF I found above is very interesting.
All the settings are in "resources" a la Windows registry. These appear related to the various conf files, but not clear in which direction - it may be the files are derived from the resource settings or vice versa.
Look at the resource related commands in that second PDF. Beware rls -r recursive option - it spits out a LOT of data!
Unfortunately rset doesn't appear to work on image size, but have been able to set user settings using it.