Another possibility would be to carry signs that are racist or highly offensive but have organizations like ANSWER or crashtheteaparty.org on the bottom of the sign just big enough to clearly see on TV cameras. (This will take a bit of experimentation.) And then act like Levin, completely over the top. That is, infiltrate the infiltrators.
Not worth the effort. The MSM never acknowledged these LEGITIMATE Left Wingers at so called "peace" and "anti-war" protests over 8 long years when Bush was in the White House:
(Left Wingers in California confirmed the Left Wing status of these anarchists)