I kayak at night quite a bit sometimes in areas which have heavy boat traffic. I use the proper lights, etc. but have talked to some of the boaters who have almost collided with me or observed me at night. The thing they always comment on are the two large pieces of reflective tape I have on the back of my paddle blades. They obviously work well and reflect moonlight, etc. as the blade moves: all angles get covered. Cheap and effective. I even put a few on the sides of my kayak for increased safety. I know that they have saved my ass on a few close calls!
The problem with using LED, strobes, etc. are that they can seriously decrease your night vision if your eyes are exposed on a continual basis...also very distracting,
The stripes on the paddle blade work and are always facing away from you.