He knew what he was in for when he posted in GDit sounds like the guy needs help, not somebody tormenting him.
Register at his address for maximum luls.
For starters those signs would keep going missing
I like the way your mind works!
One thing I will add is that be careful, I would expect someone like that to have cctv, wether you can see it or not, and he is possibly glued to it when in his house so doing anything will probably alert him that it’s you.