Does anyone have one? @spf13, do you already have some type of vision for this?
The implementation here seems to be the easy part. Direction? That’s the real challenge (IMO). What’s the main objective? Simple content editing? Or something more robust, like a full-blown admin interface? Something in-between?
Perhaps we first need to identify the questions to ask… Then they can be answered… Then an appropriate solution developed.
Here are some questions I see. Just my 2 cents. Please chime in 
Questions to discuss / investigate / answer:
Q: What should be accessible/editable via an interface?
Potential Answers:
- site content?
- site configuration?
- other?
Q: Primary goal(s) of an editor?
Potential Answers:
- editing existing content?
- creating new content?
- changing site configuration?
- viewing site stats?
- managing users? users??
- managing site assets?
- managing theme(s):
- style options?
- current in use (activating, installing, etc)?
Q: Primary/target-users of an editor?
Potential Answers:
- tech-mined?
- non-tech minded? – seems likely
- clients (end users)?
- developers? – seems unlikely
Q: Features to include in a Hugo editor?
Potential Answers:
- create/edit/delete content
- meta-data management
- theme management
- white-labeling/branding