I suspect that the physics of floating bodies and the logistics of RoRo ships would mitigate against this.
In this regard (maybe others!) Tesla makes things difficult for itself. VINs (particular vehicles) are assigned to buyers before the vessel has landed. This means that specific vehicles must go to specific ports.
Now work with me here... These ships are not like shopping centre car parks. The vehicles are packed in nose to tail, door to door. And there are multiple levels (decks). You can't unload from the bottom of the ship without unloading the top, or she'll tip over. You can't unload from the front without first unloading the back (because the cars are gridlocked).
So... when you pack the cars in, you have to decide which cars are going to each port. Cars for the LAST drop off port go in first: to the lowest deck, and to the back of the deck. Cars for the first port will be on the top deck near the door. When you allocate VINs to buyers, you lose the flexibility of changing the order of the ports, because you have to offload specific cars at each port. To change the order of ports, you'd need to be prepared to offload (and then reload) all the cars that need to be moved in order to (i) give access to the cars you need and (ii) maintain balance so the whole thing doesn't turn turtle.
Like most things in modern life, it's complicated!