Hi Troels
This summer I decided to rebuild my CNO-mkIII from a floor stander (cabinet option B) to a stand-mount (option C). The reason is that they can more easily blend in between my wife’s flowerpots and take up less space, at least visually. From my perspective there was also something dishonest about the “awful lot of waste volume” in the floor stander version. Not to mention that it will be more impressive to hear that great sound coming from such small speakers. The plan was also to do a better job to make them look good.
It was disturbing and emotional to destroy the floor standers that I spent so many hours building years ago, but it had to be done. I wanted to recycle the baffle, and it was impossible to get the drivers out without destroying anything. 
I don’t think many people have built this version of CNO-mkIII with cabinet option C. I have attached some pictures of the process and the result. 
This is the third time I have built CNO cabinets. Each time I become a little bit better and learn new tricks and skills. Perhaps you have this covered in your Tips & Ideas section, but I will also share it here so that other amateurs can learn from my mistakes :
It’s hard to make a straight cut. It may look and feel straight until you glue the box together.  My solution was to buy smaller mdf-boards instead of one big one. Then I have many straight sides and corners. This is the first time I don’t have to hide gaps between the cabinet and the front baffle with black silicone.
I got some bubbles under the veneer. This is the solution I found on the internet:
“Use a sharp razor blade to cut a tiny slit in the bubble, following the grain of the wood. Put a small amount of wood glue or thin CA glue into a syringe and inject it inside the slit.”
I don’t have any syringe in my house, and I don’t think that the opening of a syringe is that small. I attached a plastic straw to a wood glue bottle using a strong tape. The tip of the straw can be pressed flat so that it can easily be inserted into the slit without breaking the wood. 
Last tip of today: use a bit thinner mdf-boards to build the cabinet. Afterwords glue 3 mm mdf on top of it. Then you will have very few joints that can be visible through thin veneer/paint.
Kind Regards
Tore