Why does the user care if its watermarked? Surely there are only some use cases for this stuff where it matters. Most of the time isn't it just people having ephemeral chats where this wouldn't matter?
Just to say, maybe give it a little time, but a watermark like this is not going be thing that decides someone's reaction in the near future, just what it says. (I am just betting here).
But its going to be an uphill battle either way if you are really getting the model to write everything, I do not envy that kind of project.