Chad,
I have a Canon, so don't know anything about specific Nikon lenses, but generally speaking, I use a 70-200 in the boat for wakeboarding. It is true that you won't be taking pictures of 'others' in the boat with that lens, but if you use something that maxes out at 70, your wake shots are going to always have a lot of water in the them, and not much rider. You can of course crop seeing as how you have a lot of pixels, but IMO it is not ideal. Unfortunately, the purchase of your camera was only the tip of the iceberg...welcome to the world of 'dang, that lens is expensive but I need it!'