One must consider that there are more downsides than merely who suffers. For example, no scheme could be perfectly secret, so children would know they had been "violated" while young. Would this emotionally harm them? If so, would we be able to prevent that harm when they found out through some kind of treatment? Would that treatment harm them? How much would all this cost?
I think we would have to start with a set of axioms: define the role of government, agree upon methods of psychological assessment, and agree on how to run the cost/benefit analyses. Once those are established, couldn't it work?