Stretching Quadratus Lumborum?
If I may add one more that the client can do on thier own:Stand with feet shoulder width or slightly greater apart.With hands on hips, extend the right arm (if stretching the R QL) to a 12:00 position.From the hips, lateraly flex the spine to the left until just before the right foot begins to come off the ground.I got this from my MT, who also is a yoga instructor, and I have found it to be very helpful. Hopefully it makes sense in written form.