I recently resigned from a 500+ bed academic center, and we encountered those very same patient populations, with similar LOS due to behavioral issues. The solution at this particular facility was to have a secured wing of the hospital, about 25 beds, for these patients. They were able to ambulate within the unit, and there were psych trained RNs and techs that WANTED to work that unit. Only those that were truly bed confined would be placed on other units to make room for those ambulatory pts who needed to be secured. There was also a security officer stationed in the unit 24/7, but they rotated out every 4-5 hours so the patients couldn't get too comfortable. Another reason for security was the doors to the stairs on that unit were locked, and only security and the charge nurse carried the key to unlock it at all times.