The toilet should solve the problem of ventilation, not lighting. If the ventilation problem is solved, there is no problem at all just installing the power switch outside the door. Every time I go in and out of the bathroom, it's on. Which star hotel's bathroom is not like this? (But people have special ventilation pipes. )
However, it is not feasible to open a window on the bedroom wall from the perspective of aesthetics, use and geomantic omen.