Back to the window leak: Form the photos you provided it appears that the window is set into the window opening with only a rubber gasket much like used to be used in auto windshields. #2 in my photo. A piece of rubber split so that the window opening sits into a slit of the gasket, the windshield sits into another slit on the inside of the gasket and then a piece of "spline" is set into a channel of the gasket tightening it against both the window opening and the window itself. I can't see the inside of the window area and that might be where the spline is, or is supposed to be. I'm betting that it's missing. The outside appears to have had some type of sealant applied. At #2 on the photo, between the gasket and the body of the camper, this should not be necessary IF the gasket is properly installed with spline. A window with that type of gasket should move slightly as the camper moves along the road. Again an IF, any sealant material is needed I would recommend a sealant used years back made just for auto glass. It's black, messy, sticky, and sometimes referred to as "sheep snot". Auto glass dealers/installers and auto body shops used this when installing an older windshield and sometimes back windows to keep it water resistant. It never hardens, stays pliable for ever it seems. At #1 in my photo it appears that there is a hinge that attaches to the camper shell. How does this hinge attach to the campers shell and is there any possibility of water intrusion at the point the hinge attaches to the shell? As much as you don't want to hear this: I'm thinking that it is time to remove the complete window assembly, clean all parts and edges, then re-install one step at the time, as I'm sure you have done.
2015 FR Freedom Express 310BHDS pushing a 2014 GMC Sierra CC