You don't need film backing paper to experiment with the counter. Just use any kind of continuous paper, like cash register receipt paper or butcher paper, etc. You can tape it onto an empty spool. My own Yashica-D has sort of high pressure on the film counter wheel that pushes against the film. Every roll I develop from that camera has little tooth marks visible on the margins of the film strip. The little grippy wheel doesn't actually pierce the backing paper, but the little track is obvious. The film counter gear track allows me to distinguish negatives taken with the Yashica from my other 120 cameras.