Glad you found the placard holders.
We have since added two more placard holders to the sides of the truck. We have had to run more then one placard on HazMat loads and then we added a set of explosives flip placards. The explosive flip placards have made our life much easier then having to wait for someone to find the correct placards.
Our front placard holder is removable and we only have the holder on the bumper when needed. If we have to run more then one placard the second one is stuck to the bumper.