I agree w/much of the immediately prior opinion. However, putting the 70-200 on the “cheaper” camera body means that likely you are detracting from the sharpness of the 70-200. I would put the 200-500 on the higher megapixel body. You will likely be using a mono or tri pod with that lens which might give you a sharper image. The lower megapixel sensor will be “improved” by the super sharpness of the 70-200. As much as I like the sharpness of the 200-500 I cannot imagine hand-held shots at the far end will be consistently sharp. Someone else mentioned the Sigma or Tamron zooms that go out to 600mm. I found my Tamron G2 to be very sharp at 600 although it too, is tough to handhold. Good luck with all the info a number of people have given you. I really did like the suggestion to get a second body. Used D800 and D810 models are becoming more and more reasonable in price and there are many available.