Good luck.
However, I'm just going to throw this out there. In the grand scheme of things, even if 75% comply with your DMCA notices your bottom-end won't go up much.
The sad reality is free porn is free porn, whether they're watching yours or another copyright holders. This won't change anything to better your situation. Once you DMCA them, yes, they won't be infringing on your copyrighted works. However, it's not like after removing your content a banner or even a sponsored video remains on their site to reference your site, you've just lost all the exposure, (even if less than 10% of it was productive) that was coming from those sites.
Instead of DMCA notices maybe you should first propose an opportunity to monetize their users that can benefit both of you.
For example, offer a major tube site a sub domain name with their branding and some sponsored clips. I know, I know 'supporting tubes' I'm evil, but do what you need to do to 'adapt'.
Unfortunately for us, those tube sites hold A LOT of potential exposure in their hands.
Until we have effective laws that can shut them down completely, working with them instead of against them might end up being the most productive solution, (yes it hurts to come to that realization).