You may be right. However, the other three drawings in the same article are 15'6", 16'6" and 16'. If he was using a 'generic' drawing and filling in the lettering all the drawings would be the same, and then I 'might' agree.
Sorry, the drawing is an outline only, with details of the lettering. Copyright would prohibit me from posting. Details of the builder are not shown. 16'6" over headstocks, 9' weelbase.
Lacking a colour picture, I painted my box with blue bricks, because most of the type 5 boxes I'd seen were in that colour brick.
Then I found a colour picture ...
Although I've been there several times, the Wrangaton box has never been open. However, the box at Drws-y-nant was similar, a couple of pictures of that.
Clearly you haven't read the works of Peter Denny. You are describing a different phenomena. The buffers should not be in contact when pulling. Therefore they will not cross.
You can only get buffer locking if you have reverse curves, so look to eliminate those.
Or do you mean the couplings are too short, resulting in stock being thrown off?
I used the original Bachmann coupling/connecting rods, and using Exactoscale bushes in the oversize holes.
There is a slight discrepancy between the centres, but this can be accommodated by jiggling the bushes. A very smooth running 45XX is the result.