I bought a SiOnyx black low light camera and an infrared flashlight. Tests on the water with no moon, and a few clouds, shows that the camera by itself works well. I can see a bridge that is 1.1 miles away clearly, and boats moving by it show up well. The shore line across the water way (.4 mile) is clear.
Where it really shines is combining it with an 850 NM infrared flashlight. A tight beam illuminated a target like it is day light as far away as a half a mile last night. A wider beam lights an area up but has a closer range. I think I would only need to use the IR flashlight on a very dark, overcast night.
It has its own WiFi which your tablet or phone needs to use to access it. The latency is acceptable, about a half a second. It comes with two batteries which are supposed to last two hours, so you would have four hours max without recharging.
I think I will use this with a tripod with suction cups, as a temporary back up camera, then permanently mount one of the recommended versions provided in this set of posts and then the Sionyx will be used while underway at night. They are just beginning to sell a marine permanent mount SiOnyx camera for $1599.
Meanwhile, as folks read this thread and have adapted other solutions, it would be great to hear about them.