If a guy is into domination and likes playing with like minded women, how can he protect himself legally?

So let’s say a guy is into cnc and some other domination kinks.
Is a verbalised “yes I’m into this” then filming the whole fun time(not in secret) the best way?

Because think about it logically, if she gets a hickey, or a bruise from being moved around/being restrained, it would actually make sense why the police would think she was forced. Understandable.

And there’s no actual way to tell, without proof.