Add the Haven as your in & outbox, I believe it has special urls for both. Having one inbox might make you miss comment, reactions & zaps if people can't reach it for some reason though.

Lots of clients now use outbox, so if your Haven relay is not reachable they won't necessarily look to the relays the notes have been blasted to, and people might not see them. If using a single relay make sure it is reliable, and people can read and write to it 💯