We had a similar problem with a neighbor a few years ago. They just wouldn't stop smoking right next to our house. So we made sure when we picked up after our dogs that the bucket of fresh dog droppings were placed right next to their favorite smoking spot with the lid on. The dogs would get picked up after every day, and I'd conveniently forget to put the lid on the bucket or take the trash out on trash day. Took 2 trash cycles for them to find a new place to smoke.
Good luck with your neighbors. You could also try talking to the actual owners of the house about what is going on. Depending on the relationship you have with them they may be able to help. I'm a landlord as well and go out of my way to make sure I have good relationships with all the neighbors since they act as my "eyes" on things I can't always be around to see.