I know nothing about the surf in NJ, but if the waves are small trying to surf a shortboard, especially without experience, would be folly.
I don't know why you're worried about being able to duckdive since if the waves are small you shouldn't need to. Turtle rolling should be an adequate method to get bast broken waves.
As for looking like an ass, well, I personally think longboards are cool, especially when surfed well. I'd love a longboard, but since I have to get on a busy train to my local spot with my board I had no hoice but to get summat smaller.
Oh, and I reckon if it's small most the time a shortboard would frustrate the hell out of you. I ride a fish which a super wave catcher and still wish I had a longboard on those small days.
THis is just my opinion anyway (maybe not that reliable since I ain't been surfing that long

)
...J...