Why do you assume someone with pedophilic urges doesn’t realize that acting on those urges would cause harm? To quote one of the admitted pedophile posters:
We distinguish between people with sadistic urges and fantasties and those who actually engage in criminally sadistic acts. We distinguish between people with rape fantasies and those who actually rape. Why not distinguish between those who have a pedophilia urge and those who act on it?
And THAT is why you are unlikely to have any volunteers for your research. Those who can control themselves will struggle on in silence rather than risk losing their freedom for wrong thoughts rather than wrong actions.
Like what? Suicide, perhaps?