You could do a late 1800's type dress with a bustle in the back, only make it a mini skirt with the bustle part longer in the back and army type boots. You could cut the top out of the top hat so that it was just hanging on by a couple of inches, ...
I love it and I have invited Leslie to join too even though she said she didn't have any Halloween I told her to start something and I think she likes the idea.