Solaris T-2653: Moisture in back wall

[Chrisco1963]

My wife and I recently purchased a 2000 Solaris T2653. When initially inspecting the camper before we actually purchased it, I brought a moisture meter with me to get various readings on the walls and ceiling inside the camper. There were only a couple of places where the readings were somewhat "high". One area being the front left corner (where an exterior marker light is located), with a slightly higher reading and the other area was near the bottom of the rear wall off to the right bottom corner of the rear window, with a significantly higher reading (than the rest of that same wall).
Nearer to the top of the wall, it read between 0 and 1%, whereas in the lower right area of the wall it read between 14 and 16% moisture.
To the touch, it feels colder and the wall in that area of concerns seems to be detached as there is play in the wall and not tight as it is in the rest of the walls.

Has anyone experienced similar issues and have any ideas, if water is getting in, how to fix it? I have not found any holes near the top exterior side of the camper (but then again, the moisture meter did not pick up on any moisture near the top of the interior wall). There is a rubber glass seal that seems to have shrunk over time (as there is a 1" gap near the corner of the glass, where the ends of the seal to meet together, but that gapped seal is on the opposite side of the wall where the higher moisture readings are). I am wondering if the aluminum siding on the exterior of the back wall could possibly be separated in some way as to be letting water get in?
Note: The moisture meter I used is a KleinTools ET140, with the mode set at Drywall

On the bright side, the camper itself was very well taken care of. After refilling propane tanks, filling the water storage tank, and cleaning out wasp nests and bug carcasses from the water heater, refrigerator, and furnace lighting areas, we tried every component in the camper and found each to work very well! Also, not only did the camper come with a 3" original Sunline binder of every piece of equipment installed from the manufacturer, it also came with two leather Sunline embossed drink coasters, a cutting board and two Sunline embossed baseball caps!
We are the third owners of it and are excited to use it for camping toward the end of this month (July-August 2023).

I just rechecked the back wall for moisture again tonight after a past few days of heavy rain.The following are a couple photos to indicate the readings on the moisture meter...