Honestly, I don't even think it would require any marketing from out end. If the application is made, within one year I'd figure it would be as widely know as the "it's OK to be white" meme. 4chan and random youtube political commenters would talk about it and it would spread. And I figure you could get a decent amount of women using it if there is an option you can select to filter out the men who want casual sex vs breeding.
it will take marketing.
mass marketing is what it took for black men and white women to pursue each other in the main stream. it will take similar marketing for white men and black women to become to pursue each other in the mainstream.
and the problem with free dating apps is how they make money.
they basically loose customers when they work correctly. so they are all rigged to work incorrectly. to match people who are doomed to break up in a few weeks. that way they come back to the app, and keep using it.
also, the problem with internet culture, especially right wing internet culture, is that it's male dominated. if "wintr" became as wide spread as "it's okay to be white" it would have a 95% male user base.
to make such a dating app work, we need real world marketing. we need normal black women in the ghetto to know about the app, think positively of it, and use it. it needs mainstream appeal. such as a celebrity endorsement. imagine what would happen if someone as big as Megan the stallion said she met her boyfriend on the app. or even what would happen if a few fat black Instagram influencers with 10k-100k followers said they found their BF on the app. that's how we get a female user base.
also, fat women are good for a start anyway. they are insecure. they'll take any man who will have them. if even a lowly fat woman has overwhelmingly positive experiences on the app, they will tell their more conventionally attractive friends about it, and thus mainstreaming the app.