Roof Leaking, Cant find source

[SNGLESHOT]

OK... 27 ft Zinger Camper trailer. 2006 model. Been fine up to now. I now have a leak showing on inside wall Left Front Corner. Checked roof and seams. All look well. Checked seals around vents, vent pipes, AC unit, TV antenna... all areas that would require a break in the roof integrity. Question is this: HOW DO YOU FIND THE SOURCE OF THE LEAK??
I have been reading up on this and I find that the water can enter at one spot, travel quite a distance to another spot to eventually manifest itself by showing up in a wavy wall or a stain inside a cupboard or something to that effect. But nowhere in my reading does it say how to find the source.
I tried to initiate or reproduce a leak by having my wife hold a garden hose over sections of the camper while I was inside looking for a leak to show. Nothing. I figure it is behind the walls. Any ideas??
I recently purchased some Eternabond sealant tape and plan on hitting all seam and entry points topside. Thanks in advance for any replys. MAJ D.

 

[Hoefler]

It could be your A/C leaking condensation into the unit. Also, if the unit is used in the colder months, it could be condensation out of the air. When closed up and used during the colder months, you will get humidity from every day things, like cooking, bathing, and just you being in there, etc. .

 

[HBarlow]

Windows and doors can leak also and often do.

You are correct about the water migration. Water could be entering over the front window or a side window and migrating into the corner where you are seeing a wet wall.