Can we waive child support in an uncontested divorce?

My husband and I are separating amicably. We want to jointly file for an uncontested divorce in Chicago where we live so that he can move with our older daughter to Texas as quickly as possible. Our daughter is very gifted and has a scholarship to an art school there. Our younger son is going to continue to live in Chicago with me. My husband earns a lot more than me but we’ve agreed that he won’t pay child support because we’re each going to be raising one of our kids and he’s going to pay all transportation costs for them to go back and forth between Chicago and Texas for visits. I know child support is mandatory in Chicago but under these circumstances, can we waive it in our uncontested divorce proceeding? Would we need to tell a judge why my husband isn’t paying child support? Also, do we need to put the agreement about the transportation costs in writing?