Judy IMO the window gasket would be my first place to look. I swear it may look like the 2 meet but have found that not to be the case with mine. In my trailer when I discovered it was leaking I found water pooled up on the upper ledge that the bunk attached to ( I assume were talking the front closest to the hitch) and rolled its way down behind the ensolite. Check the curtain rod rivets and also the rivets that hold the front guard on those loosen frequently.
Water also for me leaked in via the vent right behind the fridge
. The rivets were old and weak. Water wicked in here via the belly band and kinda rolled on in real slow like up and over into the vent. Check and see if that might be the case, open the vent behind the fridge
and see if its wet here, it could have sloshed on over to the front bunk compartments.
If that's not it I start a slow process of find the leak by placing duct tape over the suspected (or even unsuspecting rivets) and pour water over said rivet. I usually start from the bottom working up to the belly band.
If that fails what I have also done to find a leak is wait til its raining and walk out into my trailer and see if I can spot where its trickling down. It works best for me when the trailer is dark and I shine a flashlight near the edges. If you are referring to the back side of the trailer in those compartments well let me know I'm good at spotting those leaks
I will say 1 rivet can make a whole lotta water and it might not even look loose. Water on plain fiberglass leaves a tiny trail like a slug trail its can be white or darkish. I would not tear into the ensolite if you didn't have to.
The Black seal around the bottom is just ornamental and to far down (at least on mine) water is more than likely not from this source unless there's some gaping hole hidden underneath. Good luck!
Just my 2 cents