If you want a sunset shot through the gaps it has to be at low tide, as you need to be on the 'other' side of the rock. You can't access that side of the rock at high tide.
You're more likely to get a shot through the gaps at sunrise, where you can be on the safe side of the beach.
It very, very rarely lines up in a way that will let you get a shot of the sun through the rock.
Low tide will be too low for what you're expecting to achieve. You'll need something towards higher tides, but not a full high tide.
It's a wonderful location but the direction of the sun and the tide times mean everything lining up perfectly is incredibly rare.
I agree.
To get to the eastern side of the rock you need to be there at, or near, low tide.
There seem to be very few photos from that side and one I found shows a headland through one of the openings so you may not get the sun descending over the ocean.
The narrow, slot-like openings define the angle that you need to be able to see straight through, which in turn determines the position of the sun.
The alignment will need to be quite critical.
The Photographers Ephemeris and in turn, Google Maps, do not mark the rock position accurately, so you can't rely on them for precise alignment.
Don't forget that you can't park anywhere near the beach and it's quite a trek to get there, and the last bit is quite steep.
I think this idea will take quite a bit of planning, and possibly a recce or two, but the result could be worth it, although s@ds law says you'll be there, all set up and ready for the shot, and the sun will disappear into cloud at the critical moment!