If you are truly done, I really think you need to do this legally. Because when she does get a boyfriend and you are supporting her without a legal document, you aren’t going to like it very much. And I wouldn’t really listen to her saying “she won’t be dating for a while” because I bet your bottom dollar the second she finds someone who sweeps her off her feet and offers her something financially, she’s going to drop that tune.
Why aren’t you doing this the legal way? You really want to open yourself up to the many things that can go wrong?
Honestly, if you are truly done as you ya you are, you would be a fool to not protect yourself .