Eric, some more questions, if you don't mind, since you're way ahead in customizing the NX.
1. When you say get power for the camera with an add-a-fuse, is this what you mean?
Amazon.com: Bussmann BP/HHH ATM Add-A-Fuse: Automotive If so, won't that mean the black snap-on fuse tray cover will have to stay off? Any reason not to just add a fuse in an unused slot and connect the power lead at the back of the fuse tray? What amperage fuse did you use? I'm thinking 1 or 2 amps. The monitor comes with an inline 2 amp fuse.
2. Where did you grab power for the monitor? I was thinking I'd just draw off the same source as the camera. Did you bother connecting the blue wire to power, in addition to the red? The instructions are worthless, but from the reviews the blue is to be connected to the vehicle's backup light circuit if you want the video to automatically switch to the rear camera. Doesn't look to me like it's necessary for this application.
3. Since the CD/Radio fuse power is always on (haven't checked it, but I'm pretty sure it is), would you be concerned about the camera and the monitor always drawing power? Or will you install a switch? I read in one of the Amazon reviews that the monitor that draws enough amps to eventually run down the battery if the vehicle sits unused for awhile, even when the monitor's switched off. Not sure why that would be.
4. The patch cable that comes with the camera is 6 meters long. Great for wiring a truck, but 5 meters too long for the NX! Did you use a shorter cable? I don't know if coiling the longer cable will interfere with the signal.