Billy, everyone wears those long shorts in NZ and have done for ages. Even shorties like my hubby!! ( he's gonna kill me for that ! ) And, he looks so cute in them, very Dennis the Menace like!! lolol
The only people we see wearing shorts above the knee are the English and they usually pair them with sandals AND knee high socks.
We are a very very casual and laidback country and many guys wear board type shorts all year!!!
Dont fret about ya trews, wait until you get here then buy some of ours!! You'll see, and you will look GREAT in board shorts.