If I understand the working of the “Wedgie Sled”, it doesn’t matter if you are perfectly centered or not. If you are a little out, then the error on one side compensates and cancels the error on the other.
Naturally, it fits in with our sense of rightness that it be centered. And to that end, two pins on the sled and a slot on the wedges would make a simple, yet valuable upgrade.
Or better yet, a slot on the sled and two pins on the wedges, which would work the same way. But better, because you could flip the wedges over (pins up) if for whatever reason, you deliberately wanted a non-central alignment!