If we do want to use race as a lever for increasing editor engagement and content quality, seems to me our best shot is to spread awareness around the major race-related gaps we know about (e.g. coverage of the US Civil Rights movement) as a way of drawing attention to the general problem that racial gaps create for our topical coverage and the POV of our content.

I really like your point above Johnathan, and I'd like to second the "please don't racially profile people based on photos" plea. But in response to your paragraph above, maybe questions like this would be useful (substitute any under-covered area in here):

1. Coverage of the US Civil Rights Movement in Southern States is limited by Wikipedia standards. Are you someone who would like to see that change for the better?

2. Would you consider becoming an editor for the primary reason of increasing coverage here?

3. What are some things that keep you from becoming an editor?

a) time commitment

b) voice drowned out by the majority

c) technical challenge

etc...