I've reinforced the plastic camera stand with some right angle aluminium pieces in order to reduce the amount of wobble when the Turtlebot is being teleoperated.
Also, I've changed the cameras to Logitech Quickcam 9000s. These give a better quality image and have a wider field of view, which makes manual navigation easier. The cameras are angled downwards by 30 degrees.
The cameras are 1.15 metres above floor level, which is enough to see table surfaces and window ledges.
A possible alternative way of making a camera stand might be to use plastic tubes, with slots cut at the bottom to integrate with the button stand, and secured through the middle with a long bolt. Similar slots could be cut at the top to mount a piece of board on which webcams can be mounted, and the camera USB cables could be fed through the tubes.