I bought a fatshark with integrated pan/tilt system, but found out the hard way that it's not designed to be mounted upside down (i.e. having your camera upside down without the picture being upside down).
Unfortunately, the integrated fatshark mount is not designed to be used upside down. As sad as it is, I had to take it apart, use a soldering iron to move/widen some holes by melting the plastic, and then fill the gaps from the old holes to avoid having dust go inside and end up on the sensor (there are also a couple of tabs to break/cut out/melt away to allow for screwing the back plate upside down).
Here are the pictures: