Here is a fully working Mastcam for rovers.
To activate/deactivate the camera just right click it or you can set up action groups.
Once activated the camera will switch to the perspective of the Mastcam, use the arrow keys to rotate the view.
You can change the sensitivity in the CFG.
Created with the help of JoePatrick1, creator of Mk2 Essentials, KerBalloons and Greenscreen Mod.