Good question...I applaud your concern but not what you're using. Paper towels can become damp & stick to the rodent being swallowed. They are not digestible &
can cause a life-threatening blockage requiring surgery to save your pet, as can fabric of any kind that is used for this purpose. When snakes open their mouths wide (as when swallowing prey) their teeth can catch on paper towels or fabrics.
So yes, put something down to keep your snake from ingesting substrate, but use something like a cardboard box lid or plastic plate or plastic storage box top. Your
snake would actually be much better off if he swallowed some coco fiber than if he swallowed some paper towel... You're right that many people don't bother about
this ("snakes ingest stuff in the wild too") but I prefer to do the best possible care for my pets, which means common-sense (& EASY) prevention of medical problems.
I always watch him eat 100% of the time to make sure he doesn't swallow any, but I will swap to something else like u said to make sure Thank u!