I am DON in mental health and addiction hospital in Saudi Arabia. I understand exactly the kind of situation you faced and will likely face repeatedly in the future.
We routinely have around 20 constant observations in three units. Some are real, others are imagined. I won't go into the 'medical dynamics' but suffice it to say, as the only American and westerner in the facility I am often at odds with the 'cultural differences and approaches' to issues such as ordering special observation status.
As we are a specialized facility I strongly support and advocate for our patients and my staff. We try to keep a strong connection b/tween nsg adm and staff. The good thing in my position is that I have the full trust of the hospital administration to run the department as I see fit so I have significant decision making authority.
I don't know the organizational culture of your nursing department. I read often in these pages of a divide (real or imagined) b/tween nursing staff and the nsg administrations. I remained amazed at the lack of support and connectedness our colleagues complain of in facilities back in the States.
I agree, that documentation is a very good idea. Avoid editorializing and clearly stating your safety concerns for patients and staff. I would not point any fingers, at least not in initial correspondance and better to voice your concerns over the lack of leadership in a direct meeting with your DON, if you believe s/he is competent to consider your concerns professionally and act upon them after a careful evaluation of the issue. If s/he refuses to act upon it, consider a job search
to a facility more conducive to your level of practice and commitment.