klpoppe is right on the money.
On these jackknife sofas, convert it 1/2 way so that is a "V" shape, then you can simply swing the bottom pannel up.
On our 26BH, we used this to store bulky excess food items like bottle water, beer & soda, as well as spare paper products. Things you need, don't access all the time, and take up way to much storage space in cupboards.
2007 Chevy Duramax LMM/Allison
2012 Jay Flight 29QBH
2012 Jay Flight 26BH (Sold)