I recently mounted a TV in the bedroom of my 8529IKBS.
The wall was marked (with a sticker) and it was an outside wall.
I contacted the factory and was told DO NOT use screws with a total length longer than 3/4" to 1".
I was also told if the TV is to be mounted on an outside wall the factory backer plate would be metal (I was skeptical) and if the TV is to be mounted to an interior wall the backer would be wood.
To test... I took a magnet and much to my surprise, the backer was in fact metal and the magnet showed exactly where it was.
I did find the metal backing plate was not very thick (maybe 1/16") and I used tape wrapped on the drill bit (for a stop) to be sure I didn't run the bit in any farther than necessary. I had measured the outside wall thickness where the outside shower is located. The routered holes for the supply lines were plenty oversize so I was able to get a tape measure in the hole and measure the wall. My outside wall thickness is only 1-1/4" total. (fiberglass skin-styrofoam insulation-interior luan sandwich)
I used 3/4" self tapping screws (6) and it made a fine job.
We just returned from a 1600 mile trip and the 32" TV never moved.
I would guess if it was an interior wall, the possibility exists that longer screws could be used.
2016 Flagstaff 8529IKBS Diamond Package 5th Wheel
Ford F-Series SCREW 4x4
TST Tire Monitor - Sinemate 3500w Gen.
2016 Nights Camped = 44