You need to contact an attorney; call the local Bar Association, and ask if they have a list of attorneys who handle traffic violations. The violation may be the result of a local ordinance.
Your attorney may also be interested in contacting the local ACLU chapter, since the alleged "violation" may be a pretext to silence the content of the message (that is, whatever the alteration is supposed to "mean"), which is a violation of the First Amendment. (That is, unless the government can show a compelling interest in regulating the message.)
Your attorney may also be interested in contacting the local ACLU chapter, since the alleged "violation" may be a pretext to silence the content of the message (that is, whatever the alteration is supposed to "mean"), which is a violation of the First Amendment. (That is, unless the government can show a compelling interest in regulating the message.)