As requested, please find a plan for the jacking point with dimensions. If anyone has any specific questions, please ask as it won't be going in just yet.

Apologies if the plans are a little iffy, I haven't done much drawing of this type since school and it's a tricky shape- I found it a lot easier to draw free hand. I can't really be specific about the hole for the bolt and the captive nut assembly so please don't rely on it.
It would be fair to say that my B-post pillar has disintegrated a bit, yes. Just to clarify, as I haven't said much about this, the jacking structure is bolted through the bottom of the sill (there is a captive nut inside the jacking point) and also spot welded to the vertical of the outrigger in about 5 places each side. Decay was substantial enough that we removed mine by sawing through the outrigger at the very extreme behind the drivers seat in the cabin and smashing through the welds with a chisel at the other end through the hole we made in the arch.
If you don't fancy that, there is a 'flat' on the fibreglass inboard of the jacking structure.You might/should be able to cut a window in that and then drill the spot welds out, we didn't do that as I thought we had made enough holes in the fibreglass for the time being. I will try for a photo again next time I'm underneath it.
The advantage of this is again that it would be invisible once repaired and covered in mud, dirt, oil etc.Whether it's advisable is another matter...