Hi Roger
Pen Rig??
keep what ever you use simple.
Rock city is a beautiful place to start lol. seriously the places Ive been fishing lately most would say your dreaming casting into that and honestly my first thoughts were exactly that no way can you fish that.
The Taranaki coast takes time to sus out and some years are just out right sht for ya.
Best advice I can give you is 1) if you can spare the $45.00 join the New Plymouth Surfcasting club couple of outings with these guys will have you ready for Summer (they all love Mitchel's there to) if you are really dedicated and willing to travel Opunake club is awesome to. Both clubs are in a bit of a rebuild stage and you'll never go wrong joining a couple.
2) start a dairy or calender it takes time but well worth it.

My Go to rig is: 20 - 30lb main line through a 4oz sand spike sinkler swivel and a 400 - 600mm long 60 - 80lb trace 6/0 - 10/0 hook with a pilly tied onto it.

You'd be suprised what I have pulled and seen pulled of BB beach. from the Links to the Airport fishes bloody well just need to spend the time
and capture what happened etc in ya diary.

Logan