Looks killer. We do a bunch of 2-boat surfing and find that slightly smaller wakes (less weight) can work better. You end up with less white water and more usable wake on either side. If you do it right, you can ride both wakes kinda like a half pipe.
That is sick but to be technical that is not surfing the spine. The "spine" behind a boat would be the center of the wake not between 2 different wakes. IMO this would be closer to "surfing the bowl" or "surfing the pipe". Sorry about the rant but I felt the urge to get technical as I have built a few skateboard ramps with spines on them.
Yes, technically you are right. We had trouble getting the boats up to speeds to increase the distance where the wake crested. Damn boat wouldn't go faster than 12 plus both boats are brand new LSV's, we didn't want to get closer to each other.