I agree that custody guidelines, state to state, are murky, and leave to much to whatever a given judge wants. So, were there binding custody/support guidelines, written by you, what would they say?
There wouldn't be many at all. If I were to write guidelines, they'd be fairly bare. They would consist of a proposed chart to follow in setting CS (much like now). They would possibly have a clause to have the participants counseled prior to granting a divorce, whenever applicable. Meaning if their is obvious abuse or abandonment, such that counseling would be incomprehensible, that it would not be ordered. Either party would have a right to request the now defunct fault-based divorce and show their evidence and that custody/asset split would be based upon such fault when shown.
It would take a lot of effort to write a comprehensive guideline, but what I would write would be fairly sparse with the judgement hinging on a fairly mixed panel (some divorced, some married, some men, some women, some CP, some NCP) making the fairest decision possible.
I would never want a guideline that says something must always be followed, because we can never foresee future possibilities. And I would never leave it open to the interpretation of one individual because there exists a large possibility that they are prejudiced...almost everyone has that capacity.