On my last few dives, I was playing around with concepts for stowing back-up light/s on my sidemount cylinders. I added a loop of bungee to the cylinder neck, then clipped the torch on there (bolt-snap). The torch was then stowed securely under a 3" rubber band around the tank. The torch/es were quite accessible.
Huh... this sounds interesting. I'm going to try this.
Mine are currently snapped to a chest d-ring, then aimed up and velcroed to my shoulders (I'm using the velcro loops for my power inflators to secure my lights, Hollis SMS100D). It works fine, but I'd just as soon not have them there, too much clutter IMO. I dive wet, so I don't have any pockets.
My next wetsuit will have thigh pocket glued to it for extra goodies.