I will disagree with your assessment of Notre Dame not being a flagship school. It is very much a flagship school for football in Indiana. It isn't the only D-1 program in the state, but far more people relate to ND when it comes to football. I would probably say, ND is still a flagship school for an entire generation of Irish Americans, of course your opinion may vary.
I am a member of numerous Irish boards, and would happily invite you for dignified exchange of opinion, fact, and ideas. Could I guarantee there won't be some shots from the guy living in his Mother's basement? Can I guarantee there won't be some sideways shots or a dolt trying to incite? No I can't. What I can promise is, there will be posters like you and me. People who love football, and are genuinely excited about the match up between Alabama and ND. People who want to hear what you have to say. People who want to know why ND can't win, and how Alabama could possibly lose. Why Saban is so brilliant. What Kelly can do differently. What a 'barner' is? There are million questions to ask and answer.
I will never be a dyed in the wool Alabama fan, but I appreciate the team and their fans. Having said that, there is no reason I can't be friends with Alabama fans, or Alabama fans can't be friends with ND fans. Fun, good-natured, rib poking is encouraged.