I have a simple dry darkroom. The plywood on top of the washer expands the tray surface. My print washer is a 12x15 tray. I use the fill and dump tray method. The safe light is a red Jr Lab in $8.00 silver reflector. The Gorilla DR can only be used at night. There is no ventilation so I use a water stop and TF-4 fix.
I know, it's not a bathroom but close.