Help getting 0AWG through bulkhead

I'm trying to get a 0AWG power cable through from the engine bay into the cabin on a 2010 RHD UK 6.

The only way I can see to do this (and has been done before on pre facelift cars on the forums) is to take it through the grommet for the main loom behind the battery.

No problem in getting to this from the engine side, but when prodding through it my metal coathanger stops against something hard every time.

Looking under the passenger side and I can see a plastic molex type plug with a load of wires coming in at 90 degrees, so I am assuming this is the inside section of the grommet.

To make all this easier I need to remove the whole blower assembly from under the dash so I can see the car side of the bulkhead.

But looking at this seems just too complicated without taking out literally half of the whole dash assembly.

Does anybody have any thoughts on the removal of this or to get a large diameter cable through.

There really is no other grommets or holes big enough and the bulkhead looks to be at least 2 skins thick so making a new hole is nigh on impossible.

Cheers.