Do-It-Yourself, Repairs and Fixes

Ideally you want to put a fan in the ceiling and then duct as straight as you can out of the room. If your joists are running perpendicular to the wall you should be able to find a space that isn't too bad to go straight out the wall. If you don't want to cut into the ceiling, or there just isn't enough space, Broan-Nutone also makes through-wall fans that are about as simple as it gets, this is what I have in my kitchen, and a lot of old homes have.

Is there an overhead light or is the light on the wall? There are vent fan/light combos that will use the existing overhead light wires. You will have to run a vent tube to the outside with a proper vent exit. The exit will have a flappy door thing that will open outward only.

Edit: changed “bent fan” to vent fan.

Also! Most applications will have a box that is installed in the ceiling for the vent tube to attach to and the fan sits in.

You don't say why the window is insufficient ? Anyway, how about a flat prototype Styrofoam box in front of the window, and a small PC fan connected to a remote usb-adapter ? It should easily be able to empty a small bathroom for moist air.

Cheap parts, quick to glue/tape, and it would give a hint if it is enough for your problem. Tho, you would have to make sure the moisture doesn't just condense on the cold window frame and rot it, and you will lose the heat.