There's a pretty bunch of social engineering involved with trick or treaters and one is they go where they go. So the places they go and the people who go there basically is the result of a chaotic process. If you want to prime the pump you need to not only have the houses done up, but on the day get people based on there being people. It's like seeding your case with money while busking or having extra produce while selling produce for the illusion of choice. It's not simply get decorations get destinations, it's actually kind of hard, people tend to go out of their neighborhood to get to the apt places and as such they often go to the same place year after year, so if you got nobody this year, you can't turn it around in a single year. Getting everybody on board isn't enough, you also need to be seen as a place to trick or treat, which means you need people there to get people there.
You might want to give up.