Pre-pat Agreement a Good Idea?

I am 42, divorced and I enjoy single life. I have always wanted a child to be part of my life and a female friend age 24 that I have some chemistry with, whom I share a common religious and political background, have been discussing having a child together. She would primarily raise the child, but I would provide support as needed. I am of some means, as would the mother be, but would like someone to see after me when I am elderly (keep an eye on the caregivers) and to caring on the family legacy. Should I get a non-martial parenting agreement with my female friend?