My initial thoughts.
1: Lever arm from hull to tow point is going to increase for same tow height - regular towers benefit from the fact that the boat, on plane is elevated above water, stern becomes low point. Lever arm increases boarder's pull on boat from higher point. Therefore, the taller tower to get to the same height is going to create more tilt on boat, compared to a shorter tower, forward on the planed hull.
2. Visibility of rider is going to suffer tremendously, with two large blind spots created by tower.
3. While it can be folded, it will HAVE to be folded to ski or use a pylon. Therefore any storage potential, or ability to mount speakers/racks will be negated. Therefore it will have to be "bare"
4. I find the cosmetic poor. It is a heavy looking item in the rear of the boat, the rear is where boats naturally taper off. Consider, the boats have deeper hulls, windows, deeper freeboard etc. midship. By the stern we have cosmetics that naturally taper down to nothing. This design adds components there, making it look back heavy - and in reality this looks like some sort of net laying trawler fishing boat.
5. A mobile mounting point seems both unpredictable and probably dangerous. For one you consider boat stability, for another you consider if it binds and releases, or pops/moves on the cable irregularly. Mechanically you want that to be a fixed point around which the rope pivots fluidly.
6. Finally - I feel like it concetrates too many activities around the platform, consider, you've just dropped a rider, and you turn around to pick them up. They are attempting to board the rear of the boat, while the next rider is trying to also be in the same space to deal with thier board, or manage the line. You have several folks all trying to be around the rear of the boat at the same time. Add in other stern activities, such as hot water showers, or taking a dip, and you concentrate everyone in the stern. In reality folks getting geared up are better served being in the center of the boat, letting the rider climb aboard, and someone tend to the lines easily and with plenty of space.
Justifying increased airtime based on the "zipline" and trying to show reduced injury/boat damage loading boards to racks in the rear, also trying to support that the wakes are bigger, the ride better etc... I just don't think you'll get there. Particularly with the other negatives it evokes.
You're also going to compromise rigidity since you'll have people trying to move through that space, over the stern, meaning you won't have the area to triangulate the tower that you would if you're over a windshield, where folks already don't walk, and can use the tower for assistance if they did need to.