I also have CADtools plug in which has a scale icon but doesnt seem to work to the exact size.
I am afraid you will need a script. Illy is no better at making the detailed calculations than are you, so you will only confuse her.
If all the panles are close to fit their Artboards, you may Object>Transform>Transform Each and get close with Scale, then ClickDrag each in place by the corner(s) as needed.
Maybe someone has a script.