Your Unit looks good.
Just a comment, I have the same lamp unit on mine.
I have used Clear Silicone to seal the long edges and the ends before using. It still swivels to get the correct angle.
However, My unit still vibrated apart as both ends fell off during my Around Britain Trip so at the moment it is still held together with black insulating tape waiting my attention
I attached my lamp unit to a strap made from a Laptop Case Shoulder strap with a strip of aluminium set inside. If you are having a saddler make a set of straps why not have them make a matching H strap at the same time to fit your unit to as Simmonds now do?