You definitely have to have an understanding of how the dock is laid out and how the client intends to use the dock. I don't like to install dock lights until all of the other boating / tie up infrastructure is in place. (Cleats, Whips, Swim Ladders, etc etc) This way you can be sure not to position the fixtures in the way of lines or entrance / egress points.
99% of our docks here are cedar 2x8 boards & fascia mounted over steel pilings and frameworks. I use 2" or 3" long Stainless steel Truss head screws to mount the fixture to the dock boards. This creates a very sturdy installation with little to no damage to the decking. I have actually seen a 26' Sea Ray that was mistakenly tied to a dock using the INTEGRAliters as cleats! No damage to the fixtures, dock or boat.
There are of course other alternatives, Both VISTA and Hadco make "beacon' fixtures that can be used to light docks, but they are tall, obtrusive, sometimes composite in construction, and offer a 360 deg. glare filled light output that is not DSF. For residential applications, they are not very appropriate. They look like miniature light houses and are horrible things to look at all day long.
Have a great day.