I have had success in using a single small screw and a small bead of 100% silicone all the way around the inside back edge of the frame. On my previous trailer the pictures stayed put and when I went to sell the trailer I carefully used a small flat exacto blade inserted along the edge to cut the silicone and release the picture from the wall. The left over silicone on the wall pealed and rubbed off very easy. A small dab of white dap into the hole and you could not tell that a picture was even hung
. I have done the same with my 2008 8317SS.