This might be an easy mod to get started, using the existing content.

Just convert some of the hair, clothing, maybe even eye/face selections to make them work for both male and female sovereigns.

Once you're done, write up a detailed walkthrough and/or post a video tutorial.  The same techniques could be applied to converting mod content in the future.  Say someone uploads a mod containing demon eyes for the wraiths--you could then easily convert the demon eyes to work with trogs.  This would also be a step towards creating your own original hair, clothing, eyes, faces, and so on.