Hi-vis, a snappers enemy

I often go to shoots where hi-vis jackets and vests are everywhere - development sites, emergency services etc. The reflective strips on the hi-vis equipment is so good that any use of direct on-camera lighting will bounce straight back to the camera and blow-out the strips or confuse the camera, in both cases the images look terrible. On sunny days when extra lighting is needed to see information in the shadows - especially under the peaks of hard hats, what can be done? Often it is unsafe or unpractical to get photos of the subjects without their hi-vis so off-camera wireless flash is used to create side-lighting, as I have done on these recent jobs: