Get a polarizing filter and/or see if the camera you will be using already has one. That will cut the glare drastically and some if not all are adjustable.(As the filter is turned one way or the other, you can view the polarizing effect through the viewfinder.) Also, set the camera 1 to 2 shutter speeds faster or 1 to 2 f-stops higher to help reduce glare. Bracket your shots (take multiple shots) with these different settings, don’t just take one picture at a single setting.