If you are serious about the challenge of a kingfish off Flat Rock at Tangoio then you need to do some planning and preparation. Racepics is right about the height off the water but that can be a bit of an advantage with a big fish on, It is generally shallow in close and fighting a big fish from a high position gives the angler a distinct advantage.
This is no place for light tackle if after kingfish. Best technique to achieve a hookup is by using a livebait. You can catch these on location at the lowest ledge or back around the corner on the ledge facing the beach just below the walking track. Small kahawai, yelloweyed mullet and piper are all possible live baits so learn how to catch each. You also need to have a bucket, kids blow up pool or other type of livebait tank. An aerator, battery powered is useful to keep spare baits alive. A bucket on a light rope is handy there too to get water up on the ledge.
Slide baiting will allow you to fish a couple of livies off two rod without tangling. A bait under a baloon that will stop it hitting the bottom will work but requires a lot more attention.
A long gaff could help too.
Carry in as much berley as you can and keep a constant stream going. Throwing lures out wide and fast retrieving them can also lead a kingfish into the livebait for you.
This isnt the best spot around the area but I understand your attraction to it it is a neat challenge to beable to tick it off. I did years ago and now look for new challenges. I wish you the best of luck.