Not sure if I would use the EZ Grip off of the hot shoe. Never have. Looks interesting but it could definitely put stress on the hot shoe, especially on a windy day like we had. I think the Avenger kit mounted to a tripod or the arm of the fluid head on a slider would be a safer bet. Or, the EZ Flag off of a cold shoe adapter like the ones from Nasty Clamps.
This is just a scout so we're messing around with ideas. Obviously we wouldn't use a piece of paper (in frame), to flag for lens flare.