If we are seen as arrogant and annoying, that certaintly isn’t going to get people to think charitably about Catholics. You guys think you can covert people in one easy step, but that is never going to work if you create (more) ill will between Catholics and other Christians.
Please leave flooding and other behavior for much worse sites than Christian sites. What is your end goal, and how are you going to achieve that goal by making every person that runs that site angry?
The correct plan of action- in my mind at least- is a strict discussion not about Roman Catholic beliefs, but a discussion with the members about the rules and regulations of the boards. They explicitly said topics about Roman Catholicism are off-limits. Ok. So make a topic discussing whether or not Catholics should be able to post about their beliefs just like other Christians.
There are few things Americans prize more than their beliefs in free speech, open debate and overall fairness. I believe this is the specific area you have to go after if you want to be heard. Americans like to consider themselves as good people, and I believe they are fundamentally good people. Take this route.
If you at least attempt the legalistic route first, I think we will all be better off. Incrementalism may be slow and painful, but it works.