Do you have a spirit store there. It is a halloween specialty store. I love that store for ideas. Lowes has some really neat ground breakers when you make a loud noise it talks to you and tells you to leave his grave area. I like it. Here is a picture of my ground breakers.
This guy is made out of a tomato cage with two rebars for legs and they are the stakes in the ground. I bought a latex mask and hands. We took a tomato cage and welded two halfs of a small tomato cage to the second ring in the large cage. Then welded the two rebars coming down for the legs. We dressed him in a thrift store jump suit and put his mask on and hands on. I put a light in the face mask and he is scary.
I wish I lived next to you that would be fun.
The simplest things are the scariest. Have some one dress up in a scary werewolfe costume (it works best with a couple of them) and have them just follow the people making scary noises but never touching anyone. That scares the heck out of the teens. I would also say get a fogger at a discount store and have that putting out the fog at the beginning of the walk.
Check out xmaslilly's decorations in the halloween section at my site. I will tell her you need help and see if she will come over and post some neat ideas for you.