Okay, so you have a few options. The best is training him to go where you want.
1. Take some of his poop and put it further in where you want him to go.
2. Match stick him.
3. Spray the area with tick and flea spray.
4. Add some olive oil or, honest, catlax (the stuff they use for hair balls) to his food so he has a bit looser stool or ask your vet for stool softeners for dogs. I'd call my vet tech partner but she is in India with her husband. But I can guarantee you that human laxatives are a no. Plus, you can't keep using any of them or risk habit forming.