A sign is a good idea something like
"it was my innocent dog this time, next time it could be your child, SLOW DOWN!"
Of course I am that in your face kinda person so maybe you might not want to go there.
Kay,
I didn't mean to make you sad, I know what you are going through , Someone hit my Dobbie so hard it tossed him in our yard, worst part was he was on the side of our yard, but near the street, they actually ran off the road to hit him. I heard it and told Tim some one hit our full garbage cans. We could see the tire tracks where he ran on the grass. Know I am hurting with you as he looks like such a sweet boy , most labs and goldens are never met one I didn't like.