What else is there I can say that will help ease her mind? Being her 4th child & an uncomplicated pregnancy so far I'm thinking the only thing that could cause problems is her stressing & not being able to relax.
At the same time I have no doubts in my mind at all that she can & will do this unassisted.
It sounds like you are a very concerned friend and I think your intentions are very sweet.

But it is a big difference to HB vs FB and although you are convinced it's the best thing for her, it really is her decision to make because should anything untoward happen, you do not want her to be resentful of your insistence.

My advice is to offer her all the big pros AND cons and let her decide for herself. As a good friend you'll support whatever choice she makes