Please recall, your specific question was "Is this something I can contest in court with confidence?"
Missy is telling you what she would do if she were the judge and were presented with your defense. She's not stating that you can't make the argument or that there's no hearing officer in the world who won't accept it - none of us can do that. Do I think the sign is so obstructed or obscured that a reasonable motorist won't figure out what it says? I personally do not.
So neither Missy nor I can assure you that you can contest the ticket with confidence. That's not to say you can't reach your own conclusion, that opinions can't vary, or that you may get lucky in court. It's simply an opinion that the odds don't appear to be on your side.

