I have found Aperol works as a sub for Campari in most cocktails in which Campari is a major player.
For something like a Jungle Bird, which uses Campari as subtle flavor component, I would just slightly reduce the amount for the Campari hater rather than sub.
For something like a Jungle Bird, which uses Campari as subtle flavor component, I would just slightly reduce the amount for the Campari hater rather than sub.