45/55 up to 40/60 is a reasonable starting point. 30/70 is rip off even with the kids. Monthly support can be somewhere around 10% income. You dont want to bankrupt him and give yourself a bad name. 10% of something is better than 100% of nothing.
I dont like divorce cases because it shows me how ugly the person can be behind a well calculated marriage.
If you want to use the child support to pay for the tuition, then that is WRONG. (Put law aside, this is how 3rd person look at your divorce settlement. You want to get a bad name of a divorce.)