Thanks DX and everyone.
I was a little concerned at having to drill holes in under-body parts of the roo bar as this would leave only about 10-15mm of metal from the edge where hook would be mounted. The lowest bolt for the roobar (marked A) does fit the 3/4 inch bolt for the tow hook. But drilling the other hole as shown here means drilling through the edge of the frame mount and the nut would not sit on flush metal.
I had been reading up on a number of posts about tie down points and hooks recently. I had bought the tow hook pictured as I had this on the Hi-Lux we first had and it worked well. The bolt on plates pictured in the other thread look good for use with shackles etc must look in to them.
The two holes in frame in the second photo are too small and are about 20cm behind the base of the radiator mount. I would want to be in front of everything when cable and straps are swinging around.
The Nissan mounted hook does look very solid and better bolts than the 10,000 lb "rated" hook I am (was) going to mount. Problem is the lack of retainer clip to stop straps etc falling off.
I like the bridle idea from other posts and would want to remove the factory hook if I can find a replacement.
Thanks for the ideas guys