Now this is the sort of graffiti that I wholeheartedly endorse, and encourage. An automated camera and rapid fire paint ball gun, connected to a computer program that does hand writing recognition should be mounted across the street as well. If a miscreant signs illegibly, the program targets the little boy with the paint ball gun, and sprays him repeatedly, to "mark" him. Paint ball gun across the street... or maybe cat urine in a bucket mounted on the roof's edge high above the wall... either one would work I think.
Create your own visitor map! Gray Background tones, because despite many peoples' view that Everything in the world is simply Black or White, (all fundamentalists, many engineers, few scientists, lots of confused persons, many digital thinkers) there's all sorts of shades of gray, everywhere you look. Good wine doesn't have to be expensive. Conservatives do not have to be selfish and insane wing-nuts. Liberals do not have to have socialist-abortion-producing-crystal-worshiping-gay-marriages. Racists, xenophobes, fundamentalists, and willful ignorance suck. The Earth is Much Older than 6000 years. Don't be afraid of Science, embrace it. The web's a great tool. ..in the humble perspective of this INTJ alpha male.