On my d7100/d7200, I assign metering to the two front buttons. As Mike said, its temporary. My pv button is an easy natural press for me so very easy to have spot metering on demand. Fn button, less convenient with center weighted. I need to give center weight another go though, it might improve my ducks on the water shots. I crop a lot of these anyway so maybe center weighted is better.
Something else worth a look, menu f6 (on mine), 'release button to use dial'. It makes all your button changes one handed. Tap the button, then the camera waits for the wheel to change the function. Great for one handed iso changes while supporting a big lens, but also makes metering and focus changes a little less awkward.