His site says he can make a 3 sheet frame, but earlier on he wrote that he couldn't get the PETG glazing in that size. The frame would come without 'glass'. I don't know if he fixed it.
Years ago, I made a 3 sheet frame using Graphic Dimension rails, a cut down 4'x8' sheet of plexi and a sheet of foam core. I tried to keep it light, but the frame weighs around 60 pounds. Placing posters in it is an all day job and hanging it takes 2 people. The spotlight might be easier since the frame is bolted to the wall, but handling the poster and glazing to get it inserted would definitely be something I wouldn't want to do often.