One of the things I found over the years is that the smaller the better.
When I started doing night dives I used to think, "the more light the better" so built myself a DIY 50W halogen unit and very soon found that it was total overkill.
Night dives were just like daylight dives.
Then I dropped down to conventional lights with 5 or 6 large dry cells.
But often I found I was carrying many pounds of lights ( 2 x primaries + 2 x secondaries for myself and my wife) on dive trips and many times we were not getting an opportunity to do night dives.
So looking for a solution, I saw that recent LED lights are much smaller and quite adequate for use as primary lights even at relatively low lumen outputs as their white light penetrates the murk much better.
So now I use as primary Mini Q40 eLED® Plus from UK
Mini Q40 eLED Plus Diving Light- UK - Underwater Kinetics
and as a secondary Princeton Tec Attitude which burns for 150 hours on 4 x AAA cells meaning you can leave it turned on for the whole dive, eliminating the light sticks I used to use as a third backup. For this small unit I purchased a neoprene wrist strap giving hands-free operation.
Attitude | Princeton Tec
So when I'm flying on a dive trip with tight weight limits as on many inter-island hops, lights are no longer an issue.