I strapped my Blackburn 2'Fer to the left hand Mirrycle stem for awhile. It has a wider angle of view than most similar lights because Blackburn doesn't use lenses to concentrate the beam. It's much brighter than most small button cell lights, USB rechargeable and runs a long time on flashing mode. It was quite visible without distracting me.

Eventually I moved it to the back of my helmet and have used it that way for a year. But I've considered adding similar lights to both ends of my flat bar and riser bar bikes. I don't use bar end grips so I'd need to add a Mirrycle to the right side to have a place to mount the light.

However it might be distracting in the nighttime group rides I participate in, so I'd probably turn it off during those rides. The group already has plenty of visibility in traffic.

Also, technically, a side light should be yellow/amber, not white or red. I haven't found anything like that online. The 2'Fer can be set to white or red, both in flashing or steady modes. But not amber/yellow.