BIke light holder strap

My road bike is sorely lacking in good locations to mount a rear light, but I ride in the dark a fair amount. I have an Ortlieb bar bag that I've relocated to a T Bar attached to the seat post, and I realized that it has a couple of snap connectors that I could use. They're intended for attaching a map pocket.
I don't know how durable this will be, it's an experiment. The snaps seem to be pretty positively locking, but probably if you snapped them in and out a lot they would wear out quickly. Since I plan to just snap it in place and leave it there, I hope this will last.