This is where having a good lawyer makes a difference. I would argue that your bonus should not be included in CS. Also, obviously, you should argue that her income should be "imputed" for a 40-hour week. If she is agreeing to joint custody (50/50) then she has no reason to maintain part-time status. She doesn't have to contribute equal money, just equal effort.
In my case, X's L argued that my bonus be included, and the Friend-of-the-Court evaluator agreed, but she also imputed my X's wage at 40 hours. In the end it didn't make a big difference, so I didn't fight it.
If you are looking for delaying tactics, obviously coming to an agreement about CS is one of them. And in fact, remember that you don't actually have to come to an agreement about this, or anything. That's what the courts are for.
