Just switched over, but I'm wondering what you mean by blocking DOM? are you using lynx?
CSS visited links are not able to be checked using javascript, so why are you blocking this?
Could someone add some invisible 'before: content()' (or however that works in CSS) inside of an a:visited rule, and then check the DOM via Javascript to see if that content is there?
I haven't tried this, but it seems like it should work unless there is something specifically blocking that
