We create an admin document and assemble a bunch of relevant template variables for it, categorized of course and then use
FastField to retrieve them.
For example:
[[#[[++admin_doc_id]].tv.companyname]]
Where [[++admin_doc_id]] is a context setting that has the value of the Resource that is the admin document.
There is a richtext type of Template Variable you can use for rich text. We do it all the time, for example:
[[#[[++admin_doc_id]].tv.aboutsummary]]
aboutsummary is a richtext TV that the user can input their about us summary that may appear in the footer of every document.
We don't bother with clientconfig because it's not context sensitive or aware.
Of course, the migxdb method may be better and a method whereby you can do a custom manager page that is not a resource but for regular non programmer folk, this method works well.