Steve, why not just buy a second light light the same as the one that D8veh recommended and that you already own?
I mounted the mini light onto the side of an old helmet a couple of nights ago, held on with Haibike ties, dragged out a four cell battery pack that had been laying on the shed floor for the last three years, then headed out to try it.
It was easily up to the job, with both low speed tight terrain, and with 30mph down hill, which I still need to upload.
Sadly I hadn't mounted the camera into the housing properly, hence the weird outer circle and image. But even with this cock up, and using a cheapo SJ4000, you can see that it isn't a bad set up.
edit, just crossed with your post Steve, so too late.
.