Moreover, most people either run ad blockers that hide the sponsored headlines, or else have simply learned to ignore them as they scan the page visually.

I believe what OP is doing -- what all successful self-promoters on Reddit do -- is ignore the "no self-promotion" policy, but avoid getting punished for it by posting on very niche subreddits where a significant percentage of people are actually interested in the product and so "upvote" rather than "report".