We would like to add a custom lightning component (LWC) to the header of our Community, so that it shows up on all the community pages.
We have done this in the past w/ the older Customer Account Portal theme. However, the community we're working with now uses one of the newer themes (Jepson). More info here: https://advancedcommunities.com/pre-built-themes-in-lightning-communities/
In these new themes, the header is a "Compact Header" which is configurable in some regards but does not seem to allow adding components.
i.e. it's not a container as far as I can tell, unlike headers in other themes.
So what's the best way to do this, short of abandoning this theme?
Do we need to make a custom theme layout? (https://help.salesforce.com/articleView?id=community_builder_theme.htm&type=5) And if we do, can we use Jepson as a starting point (including retaining the compact header) and just tweak it , or would it have to be completely from scratch?
There seem to be some tricky and/or undocumented aspects to this. e.g https://developer.salesforce.com/forums/?id=9060G0000005qhIQAQ
Looking for general advice here.