conditional to give forum access based on profile field

[moonclamp]

I'm thinking of creating a "battle of the sexes" group of forums.

I want a mens forum and a womens forum ... however I want access to be based on a custom profile field (gender, id=5) .. so that only men can post in their forum and only women in theirs ... not yet decided about visibility though ... I might even want the forums only visible to the relevent gender.

Also I'd maybe want a custom "you cannot post in here because you are a man" type message,

Any idea how I could go about doing it?

I'd also want to make it so once a user has entered their gender in their profile they cannot change it later.

I found this similar request, however, I don't want this to be usergroup based as I already have a lot of promotion stuff going on ... plus I already have a load of registered members so they would all need to be added to the group manually