We put a large wooden cutting board on top of ours. We put a piece of that nonskid cloth underneath it to keep it from sliding around.
Never had a problem with it falling off.
The board made a nice working surface too!
2004 Monaco La Palma 36DBD, W22, 8.1, 7.1 MPG
2000 LEXUS RX300 FWD 22MPG 4020 LBS