We had one in our 2008 Bighorn in the landing at the top of the stairs. Loved it! It was a trap door with a enclosed storage box that held a full sized laundry basket...there was not access to the cargo bay...it was actually hidden in the "basement" area where the furnace, water pump, plumbling was enclosed.
Luckily in the Landmark there is a space in the cabinet in the bathroom that holds a collapsible (net) laundry basket...a little tricky getting in and out as the door hits the toilet, but I only need to get the basket out once a week...works fine.