It's simple.
Compile a list of the names and addresses of doctors who have performed or have offered to perform circumcision.
Then publicise that list, and make it easy to find people close to you on that list.
Suddenly, anyone who circumcises is under threat of assault by every antisemite in their area. They're at least going to get a brick through their window.
The difficult part is how to create and maintain the list.
Pretty much the only people who can contribute are expecting parents, and one cannot be sure of who is being truthful about their contribution to the list.
By the way, the list would ideally include all circumcision doctors, even if they did a circumcision to treat phimosis.
Interfering with cosmetic surgery makes you an enemy of the state, but interfering with necessary surgery makes you an enemy of the state that must be listened to.