What are you using?
I have a couple of black lights that are held by suction cups. The gunwale on my Z20 is too narrow for them to work. I took a 2' strip of red led lights out and taped them to the starboard side of my boat just under the rub rail. Though they would knock your eyes out if you looked into them. They were completely worthless for seeing more than a few feet (glad I opted out of the $700 install job that I priced).
So what if a good fix for seeing the bank and or line at night in a Z20?