Well, if you have the nano you don't need to replace it or buy anything extra.
Using the R7 mount with the nano:
1) Loosen the vertical height adjustment screw and position the bracket at its highest position.
2) Remove the nano lock collar.
3) Use one of the dust boots provided. Slip it on all the way down.
4) Place the R7 mount over the nano. Push it down until it bottoms out on the vertical height adjustment block. It won't go completely over the nano but almost. The dust boot is BELOW the R7 mount collar not inside - it will just keep dust/paint out of the nano slots.
Fits perfectly and without adding any height to your setup!
Now to play around with it and see if 720p/60fps is better than 1080p/30fps for paintball.