What you can do is near the end lol, just felt like ranting, and no real insult intended.
Feel lucky that it's only $300 a month. My other half pays $300 A WEEK + child care, even tho the mother makes $13,000 a year more then he does. He only makes $30,000 - $33,000a year and about $20,000 take home a year after taxes, she makes $43,000 a year and brings home $32,000 after taxes, plus $14,400 in child support a year, so she really gets $46,400 a year to spend on whatever she wants. She drives a fancy new car, has her rent and bill's paid for from the support, and we are left to scrimp and save to even pay bill's and eat, while the woman that was screwing everything that walked during their whole marriage, and he doesn't even know if the two kid's are even his, is out having the time of her life, flinging money around on clothes, car's and whatever takes her fancy. He's been to support court and all they do is raise it whenever he tries to fight it because the judge ( woman judge) wants to punish him for leaving his ex, after he found out she was cheating on him since the start.
Like I said feel lucky that it's only $300 a month.
But to answer your question I agree with what the person that posted before me said. If you have to travel very far, you may want to use that as your main point, tho the judge may just suggest that you both meet halfway to pick up the kids.... After two year's of the whole support court with my other half, I have come to learn that when you ask for a reduction, you better have a really good reason or they will see it as an unwillingness to pay the support and take care of your child. You really want to watch that. The best you can do is find the law's for your state for support, And read what they base their standards. And look to see what % they can have you pay based on your gross income. But they can also base it on possible income as well, so if you have a possibility for overtime so you can make more money in a week, they can set the % higher, even tho you don't really make that much money every week. It's a catch 22and it sucks. If they are forcing you to pay more then the legal % of what your state base's their standards on, you can go to court and bring that up, take a copy or printout, as well as your past tax forms to show what you made every year. Then, appeal, appeal, appeal. It's a long hard road, and it's up to you if you want to walk it.
I am not a lawyer or anything, so don't go based on just what I say. I just know what my other half and I have been through.