You can get any car dash cam that has WIFI capability to view the video on your cell phone or tablet. Don't leave it out in the elements. Once you have done what you need to do, remove it and put it away until it is needed again.
Just be aware that most backup cameras reverse the image. This so what's on the right side of your car shows up on the right side of the screen. So, when you mount the camera facing toward the bow, stuff on the starboard side of your boat will show up on the port side of your display screen and visa versa. Pretty easy to live with. On the other hand, a waterproof security camera (or a dash cam) should work perfectly.
I wonder if some cameras have an internal hardware setting, or configuration to fix this, or if Raymarine has a reverse image setting on the video setup page?
Raymarine uses rj45 connector and cable to connect their camera to an MFD. I installed a rear-facing RM camera for a guy with a big trailerable Sport Fisher thinking he wanted to be able to monitor "fish-on" action while piloting. Turns out he wanted to use the WiFi mode for trailering rear view on his smartphone.