This tip works for me too. Glad to see someone else has this issue with delivery.
Truthfully, if you follow one of these from design table to delivery to table you will see they are hard to master. When out on my own deliveries I have been completely annoyed at how they travel. The hand tieds are my best solution also. FYI on the taped grids, you might be surprised at how those look when water sloshes up from the vase and loosens the tape. To counter this.......because when grid taping is done improperly, it can look awful when water sloshes.
Your cube is square.......You SHOULD be completely encircling the cube vase with the clear tape. If your vase is dry when you tape, and you take the tape completly around the vase.......And secure the tape to itself......trust me, that grid ain't going nowhere.
Just a small tip from me, follow some of your designs out the door, in your current delivery vehicle, around the corners, through the stop lights, bends in the roads, and other people's driveways. You may very well come back with a different take on your design mechanics/needs.