People have matchsticked for decades and I can supply about half dozen VET SCHOOL links that tell people to do it for dogs who have had surgery. That said, paper or wood, works fine.
Except, oh, Cara. She just leaves it in, I don't care how far you put it. The only way I got her to go when it rains is by giving her fiber in her food every 3 days. She held so long 2 yrs ago she got impacted and an anal fissure. After nearly 2 mos of hot compresses to heal it up, no more. Fiber. Yeah she often poops on the back porch or sidewalk but at least she poops.
For normal dogs, I'd only add one thing to the above… tie the dog TO YOU if it doesn't poop until you go back out. Give it zero chance to poop inside. And if you need to add a tablespoon of fiber a few meals, some green beans for roughage to make the need more.. do it. And when the dog poops outside, CELEBRATE with one great happy dance and special treat. 🙂