I decided to stick with street or ground space for the final even though I gave up on the roadkill idea. I made prints of the bottoms of my feet and tracked my existence around Evanston. I only attached the newsprint to the ground using water, and when I went back the next day, the prints were mostly gone, which I had expected--the effect mimics my own disappearance from Evanston.
An interesting unexpected effect was that the ink from the prints got on the bottoms of people's shoes and, when I went back to check on my sites, I found that some of them were gone but had new ones in place. They looked like this: