Personally, I'd be more inclined to leave well enough alone. At least in Lincoln, I haven't come across too many posted establishments. I'm afraid the more publicity it gets, the more of them may decide to post. Sure, if we could somehow make it a mandatory signage that cost the businesses a fortune to obtain, it might keep some from doing it. But, that's not going to happen. If they did make it so only one type of sign was legitimate, they would still probably make it downloadable for free as the recommended signs are now.
Also, with the current state of things, a CHP holder who goes in armed anyway might be able to claim they didn't recognize the sign that was up if someone uses a home made version or something like that. If they are all the same and posted in a similar conspicuous fashion, it would be hard to claim you were unaware of it.
I'm not totally against the idea. In fact, I'd have preferred they had done it that way to start with. But now, I worry that any publicity would only create more no-gun zones. Also, the signs recommended by the State only apply to CHP holders carrying concealed. If we push them, businesses can also ban guns in any form or method of carry. Right now, if you have your Glock on your hip covered by your shirt, and you come to a posted establishment, you could conceivably just tuck your shirt in and go on in (though I'd be somewhat surprised if they didn't either ask you to leave or call the cops - who wouldn't be able to do anything anyway outside of ask you to leave). Well, I should say, the cops "shouldn't" do anything other than ask you to leave (assuming the management requested them to do that) since you have done nothing illegal.