Hi there
Sure. You could put it in a box. Lock it away. Never reveal
it to anyone and deny its very existence. Plausible deniability!
Nobody could print or save that way. But, they couldn't actually
SEE it either.
I'm just kidding of course. LMarden was spot on in that there
really isn't a secure way to prevent this. It's a lot like locking
your fence. All it does is keeps the honest folks honest. If you
have someone who is determined, they will find a way to get past
it. You acknowledged that and said that you were simply trying to
place as many obstacles as you can in that path. And it sounds like
you have done that already.
Beyond that, unless a really clever soul pops in to advise of
some method we are as yet unaware of, I don't believe anything else
can be done.
Cheers... Rick