Command hooks or something similar that you create yourself are a great way to separate interconnects and speaker cables laterally along the back of your rack. Velcro strips work great in combination with this as well for keeping everything tidy and crossing at 90*.
https://www.walmart.com/ip/Command-Hook-Large-Clear-3-Pack/289279730
https://www.walmart.com/ip/Command-Hook-Large-Clear-3-Pack/289279730