How Can I Recruit Websites to Test New Commercial Plug In

I’m not a developer, rather I’m a long time SEO.
I have had a concept for a series of plugins for quite some time.

So after doing some recruiting, I hired a really sharp WP developer and the first plug in is essentially done except for some testing. It’s been tested on smaller sites, but the real value will be towards larger ones.

I’ve been trying to find a way to recruit a few websites with staging environments to run a test on to validate that it works as designed, but I’m having a devil of a time trying to find a method of actually recruiting anyone.

Does anyone have any suggestions?