Having tried various ways to both support the guitar and stiffen the overall construction I have settled on this design.
Key features are the heavier gauge of the timber (5mm laminations and 20-28mm widths) and a lead counter weight in the foot of the back leg. This gives the stand a considerably greater feel of solidity and means that it is very stable. I am also sourcing cork to use as the contact material at the neck and body support points.
Based on this design I am going to start production with a "limited" run of two!