He can always make extra cash by picking up a second job part-time. Where there's a will there's a way.
In AR, they would reevaluate the CS, and increase it based on the 2nd job, too. It's ~25% net income for CS for one child. It is increased for each additional child, but I'm not sure how much. My current had to pay it to his ex, and my ex was supposed to pay me. Guess which one did not pay.
people also seem to jump on the " dead beat dad" band wagon so quickly. My only experiences have been quite the opposite , With dead beat moms- so i guess I've never understood this . My own dad raised us without any help of any kind from my mother. My DH and I have always had our older kids full time, and never got the child support their bio mom owed. Even with the courts and support enforcement we only got a fraction of the funds owed- we ended up paying our attorney more in fees than we received, what a headache. 
What else could it mean?