How about cutting a pass-through vent in the bathroom door?
That would maybe let some cooled air in there without leaving the door open which would be a certain problem.
I have just been out for 2 weeks in the Scamp
and I know for sure the roof vents are indespensible when not using any air conditioning!
I tried to leave the windows
closed at night annd get a breeze going with the roof vents and the bathroom front window which is very tiny.
As long as I left the bathroom door cracked open,I would get a little draw through the trailer.
is a much larger space to cool and that little window does little for me either.
I have even considered replacing the door with a curtain in the Fiberstream
to try to even the temps out some.
I have a hard time believing that a roof vent in the bathroom at most 4 feet from the window will help much though.