There's no publicly available autopsy photo that shows these wounds relative to each other.
Wrong, Joe. Here's a photo of the FBI (read government) reenactment event. They had access to all materials including the autopsy report. Notice the stickers they're putting on the Kennedy stand in. Because there was no back throat wound, the sticker on the back of the neck is higher than the upper back entrance wound.
The autopsy photo of the back shows no wound on the back of the neck, but does show the upper back wound. Therefore, the higher up sticker represents the front of the throat wound, the same wound that Perry cut into for the tube.
So there's plenty of evidence that both of these wounds couldn't possibly be caused by the same bullet. Hence, the fudging and massaging of the record by the lawyers to come up with a way to show that one bullet magically created all wounds.