Good Mood Dampened by Mean-Spirited Traffic Cop

I got my first ever speeding ticket today. $131 for going 30 mph in a 15 mph zone at the drop-off area of the airport, which is the biggest pile of baloney ever. The 30 mph zone was clearly marked and I didn't see any signs that reduced the speed to 15. I'm going to contest it. This will be a fun chance for me to appear in court.

Hilariously, the cop was so into writing up the ticket so he could go catch another speeder that he failed to notice the tapped keg sitting in the back of the Subaru. It wasn't covered up or anything. I believe that would qualify as an open container.

(I was just returning it to the liquor store. I swear.)

Does anyone have any advice on this? Should I go with the "There wasn't a clearly marked sign" approach? Should I claim I had no idea how fast I was going, having not seen a sign, and that I was just following traffic? That's not a lie--I didn't know how fast I was going. Should I emphasize my clean driving record and argue that I believed I was going the speed limit, which I believed was 30 mph? (The, er, Mistake of Fact defense?) More importantly, should I wear my pink suit to court?