I have less of a problem with child support than I do with alimony. If a woman is able bodied and can work, why should she continue to draw money from her ex?
Our family court system is a gynocracy, although I have seen signs of this changing (thanks, interestingly enough, to some fair FEMALE judges in the state courts as of late).
An expense report just may not work.
When my brother was paying child support his ex-wife would take the kids shopping for all of their school clothes. She would turn in the receipt.
The next morning she would return all of the purchases to the stores, claiming she had lost the receipts. The stores would refund her the money and she would pocket the cash for herself.
The evil woman would then throw a party with her drinking and drugging friends.