"Humanely" is a relative term, and subjective to what you consider humane. I generally look at the relationship between health risk and a given methodology. For example, If you are unwilling to supply appropriate amounts of space for a given set of conditions, the health of your birds are at risk. Quail will not stick around like chickens, so you will need to contain them in a cage or an aviary, in addition to protect them from predation as others have mentioned, and it important to isolate your quail and chickens, as they infect the quail with diseases that the chickens are immune. Raising birds on wire, irrespective of the height is intended to benefit their health, but it is still important to provide the opportunity for dusting, access to cover and the availability to get off the wire. Alternatively, the prevention of the spread of disease can also be achieved through the increased availability of space, better drainage, and proper feeding and health care.
I would just caution you to consider that if you are tractoring your quail over ground you range your chickens on, that you are exposing them to a risk of disease.