I would suggest though, even then, I'd personally rather not advertise my having access to it even if it's only with those who also have access to it.
It's already quite easy to find other users with access to the adult area simply by checking who's been posting in there and who appears to be active in there. I just don't see much benefit in knowing who else has access yet don't spend much time there. And if you want to connect with others, why not just post something there and see if anyone responds?
Besides, I'd rather avoid suddenly receiving random PM's from other users going like "Ohai, I see you also have access to the adult area. I guess that means you're into adult stuff, yes?~ *murr murr wiggle wiggle*" ...