You may already have a solution so not sure if this will help any. We have 2017 M27 I purchased last month and put a Samsung 32" in at the TV location (10 lbs) on an articulating mount. The width of the wall is 28.5" so it only sticks out about an inch when stowed for towing. Note that there is only about 10" of mounting support below the LED light.
You would probably need to check with the factory about what ceiling support is available and the max weight. Things do tend to bounce around a lot more at the back end while towing. Another option would be to get small table to set it on then just stow it on the bed while traveling. A coax cable could be easily routed around the dinette and sofa for connecting to inside cable switch or install a separate external jack at the back.