Where are you and how did you accomplish such a wonderful feat as an open intake, no-kill shelter begging people to bring you animals?! It makes me cry with happiness that there is such a place! We're in Texas and it's a pit, but getting better little by little.
Perhaps I am not understanding you. What I read is that you want to inform the public to bring their unwanted pets and any other domestic anmals they find to you. I realize you are interested in other people's exerience, but I may be able to speak for most of us, at least in the South: we've never had any experience with this! I run a small, closed intake, cat shelter. We won't publish our location for fear of being overwhelmed--like TOMORROW. I cannot fathom having a problem like yours, but I wish I could.
Our answer for advertising is social media. Could you also buy or beg advertising in newspaper, radio, or TV media?
I agree with you that anything vaguely punitive, like cameras and signs about the cameras, would only cause people to dump the animals elsewhere. Signage at the popular dumping grounds with information on where to take the animals instead and perhaps a phone number people could call or text might help. A volunteer who could visit the populat dumping grounds at regular intervals and transport dumped animals to the shelter would be a good idea.
I am suggesting answers to problems I cannot imagine having, so I could be totally off track here.
#CommunityCatManagement