New to the Heartland world. We just purchased a 2021 Pioneer RE275. We want to install the TV mount in the bedroom but there is no sticker advising where the backer is. Our last camper was a kz & we used a magnet to find metal plate. This camper we tried the magnet & an electronic stud finder with no success. I called Heartland customer service & asked for a wall diagram but the women said no & that it should be below the plugs. Anyone know how we can make sure we are drilling the holes in the right spot?