Can I get some tips/ideas for a Ghostbusters themed trunk and treat setup?

I know it's early to be thinking about this sort of thing, but I like to be prepared.

Here in the UK, trunk and treat is still quite a new thing. I took part in one last year and handed out sweets to children in costume. This took place outside of an American style diner. My Dad and I know the owner, and he likes to do car meets outside of his diner.

He really liked our setup last year. We decked out the inside of my Dad's work van, so there was more detail than most. He wants to put us front and centre next time, so I want to make the display even better. I know the owner loves retro stuff, so I decided it should be a Ghostbusters themed setup.

However, I'm not about to just put a load of toys or cutouts in there and call it a day. I care about detail and effort. I'm thinking backdrops, lights, smoke/dry ice effects, sounds, etc.

I came here wondering if anybody had any ideas or tips I could work with while I try to come up with a baseline plan to talk with my Dad about. Any help would be very much appreciated.