Fork crown/brake mount the light, they make adapters that will mount the light down low on the fender bosses or axle skewer. I have had handle bar mount baskets that had a cut out for the light, however if you load the basket up it will block the light. You might be able to rig some sort of adapter on the bottom of the basket to mount the light to.
On one of my bikes I mounted the light to the leg of the basket (I know, your set up is not the same), however there are many ways to mount lights, other than the conventional handlebars.
Aaron
