Frankenmuth Jellystone is nice, but you're not allowed to have campfires unless you bring your own raised fire pit, city ordinance... It's also pricey, we usually do some cold weather camping there for the indoor pool.
If you decide to go Halloween camping somewhere, I would strongly suggest reserving now, campgrounds fill up fast, both koa's near port Huron are popular as is Algonac st park. We typically go to port Huron koa, they have 5 Halloween weekends there.
Another place you might want to try is outdoor adventure in Davidson, huge campground with tons to do for kids, although it's a membership type campground, but you can probably get some free camping for going through their sales pitch, we are buying a new camper this year and I think we're getting some free nights there, we plan to use them if we do.
