Hey, would it be possible to request in a future update that skulls inside spawned skull.trophy entities are saved as well.
Thank you 

We can look into this.

Do you want the same skull in each trophy every time, or do you want players to be able to add/remove skulls which persist throughout a wipe?

So in our use case. It would be a player head that admins add to the trophy. Players wouldn't be able to interact with it.
We are using it as a way of showcasing players who reach a certain playtime in outpost.

Thank you

I just released v0.14.0 which adds the maskull <name> command for setting the display name of the skull trophy you are aiming at. Contributed by m-hynek on GitHub.