I don't think you need so much weight.
I've got an XLV and when I fill up the center and the left rear ballast, I'm already able to surf the wake - wakeplate completely up, running at 17 mph.
Moomba's wake is not as high as ones of other brands however it is longer which is from my point of view a lot more fun.
Adding weight and people on the side will change the shape of the wake - it will become higher, shorter and steeper; always use the wakeplate to adjust it to have it as you like.