This has been asked for over a decade. No one wants to wear a high visibility vest plus a fall protection harness.
There are many full body harnesses that are bright, even retro-reflective however they have always lacked the requirements for CSA high visibility such as, 360 degree visibility, width of visibility strips and coverage.
Finally there is a solution that meets both the requirements of CSA fall protection and CSA high visibility. Its called the Ultra Deluxe and comes set up for your pouches or with pouches.
Also accepted as Type 3 by WorkSafeBC