Why not just ask her to make you a custom rack? If you sent her a tub to go off of, I bet they could do it. They are remarkably accommodating to custom requests.
I'll spare you from my usual 'CB-70 tubs are too small' spiel, but I would like to note my encouragement to go for a larger tub size
I didn't know asking for a custom rack was an option. What size tub would you recommend? I just really like the deli-cup holder feature of the FB70-C tubs.