I have the exact same scenario going on here with OW. She post and "likes" every meme that has anything to do with "missing someone", "true love waits" and crap like that. Her account is private, but you can still see these because the originating "wall" is not private.
She now has a BF that lives in another city, and he purposely makes things public that are specific to their relationship. Every time they travel to see each other, what they did for the holidays together etc. Everything else on his wall is for "friends only".
When I figured out how to see these post, I also checked to see what she could see on our accounts. (blocking is a joke, all someone has to do is create a dummy account to get around it). I was able to see that she could still get to WHs account and see anything that he "liked" or "commented" on that came from a "public wall".
He immediately deactivated his account and created a new one. The new one has a fake name on it. He sent a friend request along with a message explaining to people that he had to shut his other account down because of a stalking issue (no details provided and no one has asked). He only friended people that are mutual friends, so he didn't have to give up social media completely.
Immediately after that he had "anonymous" viewers on his LinkedIn account. He just flat out deleted that account completely and has not created a new one. He never really needed or used LinkedIn. After he did that, I started having anonymous views on my account A few days later, I received a request to "link" with someone that used to work on a project with my WH, but I don't know this person and have never met them. I accepted the request and emailed him asking how I knew him and if he knew my husband. I already knew the answer, since WH recognized him immediately. I never received a reply, so I terminated the link. But before I did that, I checked his list of "links" and sure enough, there was OW on his list. They work for competing companies in different cities so there is a remote chance that they might know each other, but very slim. She is going off the rails if she's actively seeking out people from his previous projects to get info on him....
Basically, he's undetectable in Social Media and for the most part on the internet. And quite frankly, I'm getting a little giggle out of knowing that she's probably freaking out that she can't see whats going on with him or us
If SM is important to your WS, then maybe creating a new account with a new name and making sure that every single thing is private. Also make sure that everything on yours is private as well.