Yup, what ever floats your boat and makes you happy. If you can afford it, do it. I did years ago. Spent thousands. Traveled the world and done more than most people dream of. Yes, I was lucky to have done so. Now my two cents worth from a guy with 60 years behind my lens. Enjoy, learn, experience what you can. Spend what you can afford. Don’t go into too much debt with the wants of the latest and greatest. Because in the end, unless you make a high dollar salary for doing so. It’s not worth the debt. I do know how the shine of something pretty can make your hands tremble and loosen your wallet. So watch out for that. Now, go have some fun!

The 16-300 will not fully cover the image area of the D800. The image shape will be a circle with the top and the bottom sliced off. I would NOT use the camera in crop mode, which will further diminish the image area, by cutting off the sides. It's a workable, though far from ideal, solution. Unfortunately the full frame equivalent lens does not exist. There are several 28-300mm lenses but they are not very good. Even Nikon does not recommend using their 28-300 with a D800 because of low image quality, particularly at the long end. The Tamron 150-600 G2 is a superb lens, coming very close to a 600mmF4 in image quality and holding it's own at shorter focal lengths. At 4.4 lbs, it is just 1 lb heavier than the Nikon 70-200 F2.8 VR II and completely hand-holdable. I have a 65 yr old 5'1" tall female friend who has one and never uses a tripod - she likes the freedom of not having her camera on a tripod, and not having to lug around another 5 lbs of gear. She also uses a D800, and primarily shoots birds and wildlife. We've hiked 5 miles on a beach in loose sand together and she did not complain about the weight.