Kyle: The earlier GoPro models only shot in very wide angle views (170 degrees). With those models, you could mount them in a fixed position on a tower, and shoot a wakeboarder going from side to side without moving the camera. Problem is, the wakeboarder would look very small and distant in the frame, so the videos were not very good.
The newer GoPros have some settings that shoot in a narrower field of view. This makes the wakeboarder look bigger, but it also means that if you mount the camera in a fixed position, the wakeboarder is likely going to go out of the frame on one or both sides if you mount the camera in a fixed position on the tower. Still no zoom. Keep in mind that if you get anything with zoom, the more you zoom in, the more you will need to have the camera track the rider, rather than staying fixed.
The GoPro is a great camera when it is being carried as PART of the action. Shooting action from far away is not its specialty.
The other option is to get a more expensive tracking mount, and a less expensive camera. Decent waterproof pocket camcorders can be had for around $100, and most of the mounts (WakeJak, Wakeye, and Trakker are around $250).