Re: lights???
I often boat in a remote open marsh area where there are no lights. You see banks, bars, poles and obstructions with ambient light and contrast (low tide is easier than high). You eliminate or minimize all lights in the boat--GPS is often not a good option if you are relying on night vision in black situations. The occasional spot or flashlight is operated high in the air so it cannot reflect off the interior of the boat.
You can see furhter with peripheral vision than straight on
Conditions change everything. cloud cover, chop, rain, fog are all things to contend with. Other unlit boats are always a danger even when you think no one else is around.
As you mention there are some obstructions you can't see (spill over dam) and the only safe option is not to go there.
I also boat at night in a busy harbor and open water, to and from a neighborhood setting. There are lights to confuse you, lights on movnig barges, etc., lights to blind you and lights to guide you. And lots of unlit stuff--the worse is the dredge equipment. Oh, and homeland security who have special ways to alert an off-course boat!
Harbor pilots tell me that boats relying on GPS often regard them as radar and become oblivious to things that aren't on the chart--like a container ship.
for night operations you need lots of experience and hyper-alertness, and as little light as possible. Keep your speed down so you don't over-drive your field of vision (and run up the back side of a slow unlit boat in front of you). Which is a real issue when you also have to stay on a plane to cover shallow water on a falling tide!