L. Neil Smith's Tactical Reflections are nice in this department. "If you're not a little bit uncomfortable with your position, it isn't radical enough. How can you be _too_ principled? Take the most extreme position you can -- you're claiming territory you won't have to fight for later, mostly...
The issue I see here, of course, is that people normally ignore online petitions. I don't oppose it necessarily, but just saying, it'll likely be ignored because they're too easy to sign people up on and waaay to easy to fake. You want to start circulating a paper petition.