[JRTJH]

Most of the "window leaks/wet wall" problems I've seen are a result of the putty that seals the window to the sidewall of the trailer rather than a problem with the window construction.

That said, there is a TREMENDOUS amount of condensation associated with single pane windows when using any trailer in the "cool part of the year"... You will find pooling water in the trough at the bottom of the window, laying against the sloped edge of that trough and the glass.

As for the mattress being wet against the exterior wall, that has been a "condensation management problem" since trailers were first designed. Water will collect where there is no air circulation, and that area, where the mattress lays against the sidewall, is a perfect place for condensation to make things "ripe for soaking".... You'll also find it behind the dinette booth cushions where they lay against the trailer exterior wall and behind the sofa, where there's "minimal air movement"....

Some windows are designed to be installed in several positions, some horizontal and some vertical. On all RV windows, there is a small "weep port" along the bottom below the glass in that trough. On windows designed for multiple position installs, those "weep ports" are usually equipped with rubber "stoppers" in the weep ports. They should be removed after the window is installed, leaving those along the sides of the window. It's a "common problem" for the factory to forget to remove the "weep port plugs" and many (maybe most) PDI technicians don't return to that area, since there's no water from condensation in an unheated trailer. In other words, check your window "weep ports" to make sure those plugs have been removed from the bottom of the trough where the glass meets the metal.

Now, after all of that, if the plugs are removed and the mattress is relocated an inch or so from the exterior wall and you still have water entering, then I'd pull the window, clean all the old putty off the window frame and the trailer sidewall and run a new strip of BUTYL putty tape around the window frame flange (start and end the putty tape at the center of the bottom of the window frame) and reinstall the window, torqueing the screws evenly in a similar pattern to how you torque the lugs on the wheels (alternating top/bottom/right/left) so the window seats against the trailer sidewall "evenly at all locations"....