Might be hard to rank on Google, but I've considered them for the purposes of getting traffic from elsewhere. Perhaps automate some posts to Pinterest and other social media sites to see if it could drum up traffic to the site. Watching the thread to see what others come up with. The 2 main ones I come across are WP Robot and WP Ematico.
I've been leaning towards just doing massive CSV imports and dripping the content using either MainWP or WP All Import, both of which I own lifetime unlimited licenses for. It might be somewhat manual, but if you can scrape good enough CSV files together, then you should be able to load up and drip huge quantities of content relatively easily. The other nice part of this is that you aren't limited to RSS feeds this way. Just some ideas.