System-wide configuration of Ptyxis terminal

I’m trying to configure the terminal (Ptyxis) on a system-wide basis. I.e. when a new user is created and they open the terminal for the first time, the configuration should be applied. Specifically, I want to change the default theme (because the blue on dark background has very low contrast).

I have recently learned that dconf-based applications can still be configured via text files by placing them in /etc/dconf/db/local.d/. This works great for most apps I need to configure, but not Ptyxis. The theme is configured on a per-profile basis. The first profile is only created when the user opens the application for the first time. A profile is referred to with some kind of UUID. I’ve tried dconf dump and put the result in the above mentioned location:

[org/gnome/Ptyxis]
default-profile-uuid='12078f8f9be68b49e10b597568a72c1c'
profile-uuids=['12078f8f9be68b49e10b597568a72c1c']

[org/gnome/Ptyxis/Profiles/12078f8f9be68b49e10b597568a72c1c]
palette='One Half Black'

So, I’m pretending there already is a profile with a specific UUID. This does not seem to work.

Does anybody know how these profiles are generated, so I could do that in a scripted fashion myself before any user actually opens the app?