But one thing I did was actually modify the source in the Barcode scanner for android. You can try playing with CameraManager.java. This is what they suggest even on the forums for this particular issue. The underlying problem is that it doesn't appear to use true DIP (device independant pixel) so the scanner window is way off for high resolution or larger tablets.
private static final int MIN_FRAME_WIDTH = 480;
private static final int MIN_FRAME_HEIGHT = 360;
private static final int MAX_FRAME_WIDTH = 960;
private static final int MAX_FRAME_HEIGHT = 720;