Thanks for the response.
Watermark might be a solution in some cases. Unfortunately, not in this one. The documents in question are complex legal and payment forms that need to be printed to exact specifications - which doesn't include a watermark.
Also, the documents will contain very sensitive, private data. A watermark would do nothing to secure this data if it could be saved and/or printed into another PDF and distributed...
I'm sure RM is a great system - just won't work here.