Normally if an area that is noted as being used for a TV mount they will have a backer board not over 1/2" in thickness (saves weight). You can check the area by using the smallest drill bit you can find and drill a test hole. Small hole is easy to cover with toothpaste or shoe polish depending on the color. In my case the backer board was below the area the marked for a TV mount by about an inch, both in the living area and the bedroom area. The size of the backer board will be around 16" square. I then used heavy short lag screws into the backer board. 1 !/4" is as long as you want to use.
I've asked customer service how big the board was and they had no idea. I suggested the go out in the assembly area and take a photo of the backer board, I guess that may go over their head to do that.
Sorry, I forgot to add the sturdiness of the wall that holds the mount as a possible problem.
If all else make you own mounting board on the outside of the wall and find the studs to screw to. You may have aluminum studs which may complicate the issue.
A call to the manufacturer's customer service may (or may not) help.
Go to the sub forum for Cherokee in the 5th Wheel/Travel Trailer/Ultra lites section and ask the question. Some of the factory reps monitor those.
2014 Palomino Puma 25RS
2011 F-150 Super Crew XLT
Days camped in 2014 - 23
Camped 2015 - 47
Camped 2016 - 51 done - 6 more planned so far