I think out moisture meter may be more sensitive, it's a cheap one. 6-9% reading on yours throughout the floor is most probably normal. Be concerned with the damp area.
It's not always easy to find the leak, but start by working upward looking for good sealing anywhere there is an opening made in the shell. The water can also travel horizontally to some degree inside the wall, but that's not what we have found. It's always been above.
I caught our leak very soon before damage was done. Have been testing with the meter since new on a quarterly basis. When new there was no leakage, the four minor leaks began after considerable towing. We travel long distances with our Airstream and it gets tossed around by the roadways.
Doug and Cheryl
2012 FC RB, Michelin 16, ProPride 1400
2016 Ram 1500 Laramie Crew Cab 4X4 Ecodiesel 3.92 axles
The Truth is More Important Than the Facts