I haven't heard the part about the Placard in a vehicle, but I suppose it could apply if the law allowed. I haven't heard of anyone having issues because a S.O.S. plated vehicle can go on the forest rds without a sticker.
My thoughts revolved around the need for a titled, plated street legal vehicle. None that I know of would fit into the 50" rule. Now a quad with a handicapped ORV sticker would not need to be plated.
as the law reads now you have to carry your placard on your quad, which is where the Blue ORV sticker should pick up. If your vehicle is parked in a Handicap space back at the lot and you get off the beatin trail then how do you show the law you are exempt under the law without carrying the placard? see how its a catch 22?