Are you asking for child support from her? If you are I would suggest dropping the child support request in mediation. Many mothers in particular will give up on the custody fight once it doesn't mean they will have to pay child support.
You have to be able to justify it in the CS worksheets though for a judge to sign off on it. She obviously isn't making much money, so many be you could have her have access to some extended time in the summer and offset the CS by giving her credit for those months.
You could add conditions though to the extended visitation, like she has a bed for him to sleep in when he is there and he comes to see you every other weekend.
Just try to be creative and fair, and maybe you will end up getting it settled quickly and without alot of costs.