Keep following this thread, wish I could work on my bike the same way, but I ride it daily.. What's that big square tupperware box, Bob?
Clearly you need to buy another CTX so you can do what I'm doing and continue to do what you are doing!
As to the "large" box, that's the rear trunk that acts as my wife's backrest and holds stuff. I found it via Aliexpress.com and is one of the few with a lid that doesn't interfere with backrest pad I made. It'll mount on a Givi rear rack. It'll hold one full sized helmet and gloves and that's about all. I found it in China and picked it for compact size and the lid design that allowed me to make a chushy backrest pad for the wife.