I haven't see many people bringing up this subject for debate at GC recently.
I think your overall framework is excellent. Whenever you draw a line you can make two kinds of errors -- disallowing good things and allowing bad things.
I agree that much of society takes a more hysterical and absolutist position on this, saying all underage relationships are bad, and certainly denying that underage people can ever have a good relationship. Those are both clearly false.
There are complications, as the laws have not just to do with facts but with "what we know and when we know it". If a man clearly rapes a young girl, she reports this, and he claims that she consented at the time but changed her mind later, he might get off due to reasonable doubt. The AoC means he won't get off if she is underage.
But within your framework, I think you have your numbers wrong. Bad relationships can happen at any age, but a key difference is that adults have to take risks for sex and love in order to have a good life -- the positive is so important that they risk the negative. For young teens -- and certainly prepubescents -- it's not that way at all. They lose little by waiting. As they age, they gain an enhanced ability to divine the intentions and character of their partner, and greater emotional stability to deal with unfortunate outcomes.
risk for trauma is a general concern for which we have developed preventive and remediative methods which are widely available for application not just by a trained professional
I think it would be news to lots of people that we have simple and effective means for treating trauma.
AOC to also do harm by preventing good sex interactions. An easy example is the 23 year old who falls in love with a 15 year old but does not act on it due to fear of prosecution and ostracism, thus missing out on what could become a relationship.
Could this 23-year-old not have the patience to wait a couple years before turning the relationship sexual? I would say his love is rather shallow if he walks away when told he has to wait.
bad just means that at least one of the two people of the interaction thinks the interaction is bad.
It includes ones they think are bad at the time but also ones that they later decide were bad. A classic case is a woman who has sex with a man who has promised to marry her. When she finds out he was lying and is (for instance) married to someone else, then that interaction becomes bad after the fact.
I have a whole series of blog posts on the broader issue: