I think it's important that you're doing something. No one has to know it was you who reported.

In terms of pictures, what I'd do is play stupid. *You love horses, you saw hers from the road and the mares and foals were just too adorable and you have a thing for equine photography. You were going to knock at the door to ask permission, but there was no sign of anyone home and you didn't see any cars in the driveway. It's okay if you got a few pictures, right? Your horses are adorable, ma'am. I have a stud who'd produce great color with this mare.*

You know, that bullshit, pretend you know as little as they do. If they give you any trouble, just smile and apologize. They don't have to know where you live, you can leave your car on the shoulder of the road or at the top of the driveway in case you have to leave quickly.