After
my adventures with the See.Sense ACE a couple of years ago, I've come to the conclusion that lights designed to mount to a seatpost with a rubber band are only any good for mounting to a vertical tube with a rubber band. So unless you've got some unobstructed seatpost (which in my case I do not), or have MacGyvered a suitable bit of broom handle to a rear rack or recumbent seat (or perhaps a spare braze-on on the rear triangle) there aren't a lot of options. Traditional brackets seem more hackable in this regard.
Maybe a suitable bit of PVC pipe could be attached to the bag loop with zip ties or similar?
That said, light loops on bags are only any use for omnidirectional lights anyway. Anything with a beam will, with tragic inevitability, end up pointing sideways at the ground or dazzling low-flying wols, wasting 86.5% of your electrons.
